I don't think reading books is inherently "beneficial." You get out of books what you put into them. If you are reading with the purpose of improving your grammar or vocabulary, then any sort of novel can aid with this. If you are looking to expand your stylistic influences for your own writing, any works can help here if you are deliberately paying attention to the style of what is written. If you want to improve your critical and analytical skills, you can do so by evaluating what you have read against whatever critical framework you want to use, others' or your own.

I think there is a commonly held belief that just by reading you will become "smarter." I don't think this is true. I think you really have to work and read with intention to get any such benefits. School often directs this type of work by forcing you to do this to succeed in language and literature classes. E.g. you have to write book reports, take book tests, do vocab tests, take grammar tests. Reading books is part of these classes to help develop your skills and practice what you've learned.

But if you're an adult reader, I don't think you will get these benefits unless you are intentionally seeking them.

Also, I don't really understand why you would call out "web novels and cliche stuff" as being insufficient texts for any of this kind of learning. I think you can do the same sorts of extrapolation, evaluation and analysis with any text, no matter its intentions, format, or origins. Many people think sci-fi, fantasy, and genre fiction generally are not substantial enough to hold up to this type of reading either, and I think that's also misguided.

TLDR: You can "benefit" from reading any books, but I don't think it's something that just happens passively from the simple act of reading.