You could just @ me next time.
I can't speak for others, but I'm not trying to undermine level designers. Just the argument for selling Mario Maker levels is a bit harder to make because while everything in a Dreams game can be user-made, Mario Maker levels would always include work from Nintendo. It's not a full on game development tool like Dreams is, it's only possible to make things within the framework Nintendo provided. (I'd be for it if Nintendo would allow users to sell levels though)
Also, there's a difference between criticizing and condemning. Nobody here is saying that you can't enjoy Dreams.