why are collections so full of incompatible art?

why are collections so full of incompatible art?

why are the most popular collections just full of incompatible art?

there are various collections on the main collections page but except the https://opengameart.org/content/oga-16x16-jrpg-sprites-tiles most of the collections contain art completely incompatible to use in a single project, ideally to be the most useful collections should each have some theme and then have many assets that adhere to the theme and are compatible, i just can't see the usefulness for a collection with a lot of incomṕatible art.

is there anything that could be done to help the curent situation? besides the obvious of creating collection with art that should be compatible