As someone who has used Bevy in the past, that was my reading as well. It is an incredible tool, but some of the things mentioned in the article like the gnarly function signature and constant migrations are known issues that stop a lot of people from using it. That's not even to mention the strict ECS requirement if your game doesn't work well around it. Here is a good reddit thread I remember reading about some more difficulties other people had with Bevy:

https://old.reddit.com/r/rust_gamedev/comments/13wteyb/is_be...

I wonder how something simpler in the rust world like macroquad[0] would have worked out for them (superpowers from Unity's maturity aside).

[0] https://macroquad.rs/