I'm not sure that screenwriters or studios care to much about this kind of distribution on the web. Screenplays for Oscar-contending movies are usually distributed widely and freely prior to voting, including via widely-known, industry-friendly blogs, and I don't know that anyone has any problem with this (unlike copies of the actual films distributed to voting members of the Academy). The scripts listed here are often available at a variety of long-established sites on the Internet. Yes, some screenplays available in book form, usually with added value content, such as production or behind-the-scenes photographs, commentary and analysis, etc. Hard copies of screenplays have been sold at comic and pop-culture shops, though I'm not sure how these are distributed or who benefits from them (beyond the shop).

Screenwriters advise other screenwriters to read existing screenplays, and the best source for someone wanting to read a lot of screenplays is the Internet. As someone who is trying to learn about screenwriting, availability of produced screenplays is a critical resource...and I simply am not aware of screenwriters or filmmakers demanding these already-produced screenplays to be taken down.