This is wildly inaccurate. There are at least a few very well known game publishers such as Double Fine that have their games on itch.io. In addition, there are more than a few critically acclaimed indie titles such as Celeste, Crosscode, Where the Water Tastes Like Wine, and others.

While I agree that I would personally prefer a more curated view, itch.io is intentionally pursuing an open marketplace and that means developers of all skills and kinds and all types of projects are represented.