Doing this in the general discussion thread even though this was posted in the "Least Favorite" because well, I don't think it's axe-grinding.
I have a term I've coined called the "Sturgeon Bar", which goes basically "yes, the bulk of fiction will be subpar, but the meaning of "subpar" varies a lot by genre." It's kind of like how a one-season-wonder Premier League team that gets quickly and unsurprisingly relegated is "bad" by the standards of the top flight, but is still objectively one of the best soccer teams in the world. It's the 20th-best team there is, but it just happens to be up against the other nineteen. Whereas a pickup amateur club where no one can even control the ball is something quite different.
Cheap thrillers, if one likes them (or other similar lowbrow fiction in other genres) have a pretty high, by their standards, Sturgeon Bar. If you're not expecting anything beyond mindless fun, and if you can tell they got the fundamentals right (which is pretty easy even by the cover/store page), you'll end up with a decent timewaster.
Whereas internet AH has an incredibly low Sturgeon Bar due to its lack of a conventional narrative. There's a difference between Marine Force One (a thriller that I've decided is the most single mediocre and middling piece of fiction that I've read) and a wikibox timeline no one really remembers.
Online AH is also hit by sample size because it is very small and niche. Instead of three good, 87 middling, and 10 memorably bad books, you'd be more likely to get one good, 18 "just people, dates, wikiboxes, and stock photos", and 1 memorably bad TLs.