I have hundreds of books I want to dump if I substitute the digital version on my disk. When in discard mode, I easily hit the 10/day limit of a free account. But that is what the favorites list is for, to spread things out over days.
Collect (I presume you mean download?) is an easy part and I agree one can download thousands of books in 24h. Skimming is very different from reading is very different from learning. If you want to skim titles/headlines then yes it's a limitation. I'd just argue it's not what books are for.
Who are you to decide what books are for, especially on a pirate site? I use libgen for research. Trying to figure out if a book is good for what I'm looking for is hard! In a traditional physical library, I'd sit in the stacks and scan through sometimes dozens of books before finding what I'm looking for. Then I'd check out those few books and read them more in depth.