I would disagree, given how the major sports franchise games and multiplayer FPS games use gacha mechanics too.
The normal in app purchase trap is time saving bonuses as far as I can see
The first type are, indeed, not easy to churn out (at least no easier than any other game). The second, though, are the sort that most third-year CS students could make in a few days of concentrated effort, and individual companies often make many, many games that are basically the same but with different assets. They're then sold with misleading ads in the hopes that a few whales will get addicted. The cost to produce them is so low that even single digits of whales buying lots of in-app-purchases can result in profit.
(There's also a third category: terrible games with a license to beloved franchises, with E.T. being the canonical example. Many of them are microtransaction hell, but more often they take advantage of the brand to sell them for an up-front price. Same strategy, though: minimize production values, market as aggressively as possible within budget, accept a relatively low return which is still net-profitable.)
It seems unlikely that you’re going to have people whaling for rare drops in a trash game with no social network. Whaling is often a status thing and benefits from network effects.
I played some Nintendo’s / Cygames gacha from a while back and its revenue numbers were pretty middling despite being pretty darn high end. Are people really making money on games that are just barely serviceable with no fan base but a slot machine in them? I find that hard to square.