First, SciHub != LibGen. Allied projects that clearly share a support base but not identical.

Second, please provide a citation for the assertion that sharing copies of printed fiction erodes sales volume. At this point, one may assume that anything that helps to sell computer games and offline swag is cash-in-bank for content producers. Whether original authors get the same royalties is an interesting question.

Third, the former Soviet milieu probably isn't currently in the mood to cooperate with western law enforcement.

Even what you call LibGen isn't LG. These are LG forks, actually running against LG and pretending to be LG. LG was set up to create other libraries on its basis. Each of the forks aggressively fights for own dominance in all ways, and they resist the development of other forks by naming themselves LG and sucking in all the funds to personal possession without public reporting. Being forks themselves, they have closed the open project for own ambitions and for money grab.

Their values are incompatible with LG, and all what's left similar is the external part of letting download books, without which there would be nothing useful to look at.

Yeah, and the herculean work is actually done outside such aggregators by myriads of smaller collections, digitizing, binding, processing, collecting, and channeling millions of handmade books into rivers of literature, for free and ready to grab. The growth is global and isn't relevant to what the forks do.

Sorry to tell.

One might suppose it's not organizationally transparent for good reason.

It used to be for a good reason, indeed, but not any longer.