This is completely false because the overwhelming majority of RPGmaker games do not use stock assets while it is other engines that tend to be more popular with developers who want to make asset flip-type games. But okay.
While asset flips(on mainly unity) are a problem too, RPGM has plenty of stock asset games too. Not even Steam like Crimson tells, this site. First page of "latest updates", i already can see built-in RPGM RTP.
Other engines don't even have anything like that built-in like RPGM does. The most popular Unity asset flips are basically a selling of an showcase demos of content packs as a game, asset packs sold on Unity stores. There used to be an influx of those on Steam quite some time ago. Those aren't even games, and it's it's clearly an actual cashgrab scam. As different people there sold "games" that are 100% identically similar to each other. This is what an Asset-flip is.
Anyways, it dosen't matter for the consumer. Who cares who produces more shit ? There are a lot of shit on RPGM, if Unity or UE somewhere has even more shit, it dosen't make it better.