That's a general result -- whether it's technical jargon, cohort-specific slang, or everyday words, virtually none of them are portmanteau words, despite tireless efforts to get them to catch on.
And it's not simply a case of neologisms in general having a tough time -- think of how successful compound words can be. "Helicopter parent," "four-eyes," "furburger," "channel surfing," "web surfing," "mall rat," "gym rat," etc. The "rat" compounds are so commonly accepted that by now most people below a certain age probably interpret "pack rat" as another example of that compound type, rather than an allusion to the animal.
Was the oral culture so dorky back in the '80s? Nope. I've looked through several books of contemporary slang (meaning, from those days), including campus / student slang, and you don't see any attempts to get portmanteau words to catch on. For example, see College Slang 101 by Eble (1989). Portmanteau coinages are so self-aware, thus incapable of spreading in an age of the space case, of "just go with the flow."
But rather than continue ragging on how dull our culture has become, I thought I'd switch gears and look at what accounts for the apparent counter-examples of successful portmanteau words.
First, I feel like an idiot every time I say or write the word "portmanteau" -- so we'll just junk it for good and introduce less geeky and more descriptive terms:
1) Blends -- formed from pieces of two free-standing words. E.g., "stagflation" from "stagnant" and "inflation." No whole words allowed within the new one.
2) Half-blends -- formed from a piece of one word and the entire whole of another word. E.g., "frenemy" from "friend" and "enemy."
3) Overlaps -- formed from a piece and a whole, but where the final syllable of the first base is the same as the initial syllable of the second base. E.g., "Linsanity" from Jeremy "Lin" and "insanity."
4) Compounds -- formed from a whole and a whole. E.g., "computer janitor."
At a cognitive level, these four types go from minimal to maximal clarity as to what the base words are, and hence from least to most likely to stick in your memory as a listener, and least to most easy to retrieve for usage as a speaker. As for sociolinguistics, real-life people speaking and listening in real-life situations aim for effortlessness -- even, or especially with playful language ("art should conceal art"). Otherwise it sounds like a belabored, narcissistic grab at status points to level up your word nerd character.
Blends are the hardest to decode as a listener and reassemble as a speaker, so almost none of them ever get off the ground, let alone last. You not only have to fill in one blank, but two, and try to predict their joining up or interaction -- a puzzle, squared. Usually the coiner will try to throw you a bone and make one of the pieces easy to identify because there are so few words that could contain that piece. What other words begin with "Vatic-" that could be the base for the first part of "Vatication"? Still, I don't want to think at all when I'm speaking or listening, so even this concession is not enough for blends to have legs.
I deny that "smog" and "brunch" caught on as blends. Rather, they sound like perfect Germanic monosyllables with consonant-heavy sound symbolism. People heard "smog" as an undifferentiated whole word, akin to "sleet," which for all we know could have been coined as a blend of "slippery" and "feet," but which could never have caught on if it didn't sound like a sturdy word of its own.
Monosyllables that begin with "s" and a consonant often have a gross, off-putting, or otherwise negative connotation in English, especially if the second consonant is not a stop consonant but "l," "m" or "n" -- slut, sleaze, slime, sludge, smear, smut, snark, etc. "Smog" fits right in, and did not behave like a blend.
"Brunch" also sounds like a word of its own -- you don't hear two pieces clanging together. At first some people probably did interpret it as a cute blend of "breakfast" and "lunch," but it sounds natural enough that the majority didn't ask questions about its derivation and just went with it. If it had been longer than one syllable and not sounded like an underived form, it wouldn't have caught on.
Think of someone trying to recreate the success of "brunch" to refer to that no-man's land of TV programming after daytime but before primetime. "Drimetime"? Fail. It clearly sounds like a derived form, probably including "primetime" (itself a compound or not, depending on the individual), but what the hell is the "d" from? If you have to explain it, don't bother saying it.
The only domain where blends appear to have any shot are technical jargon, and about hybrid artifacts in particular, such as "liger" / "tigon" from "lion" and "tiger," and "spork" from "spoon" and "fork." Perhaps a lone proper noun shorthand like "Oxbridge" from "Oxford" and "Cambridge." But they can never catch on as figures of thought or speech like compounds. In fact, the artifacts themselves are so rarely referred to -- who actually buys, uses, or talks about sporks, skorts, or ligers? That suggests that not only are the blend names failures, but so are the things they refer to. The artifact design is too ham-fisted and collage-like to serve well at whatever job it's supposed to do.
So it looks like the only genuine exception is "stagflation," which is technical jargon but available for everyday use as well, to capture a past era or express anxiety about where the present might be headed. It's pretty easy on the brain, since so few words have "stag-" as a piece -- it's either "stag," "stagger," or "stagnant," not hard to resolve. Same with "-flation" -- either "inflation" or "deflation," and we only worry about one of those. (I don't think most people have "conflation," etc., in their mental dictionaries.)
Again, look at how many of these begin with "s" and a consonant -- stagflation, smog, skort, spork, etc. Sound symbolism seems to heavily constrain what blends can even get a hearing. If there's a negative or derogatory connotation, you'd better hope one of the base words begins with an "s" cluster.
This is getting long, so I'll go over half-blends and overlaps in separate posts.