>>11,12
The link between tech geeks and anime fans has a long history. See, for instance, one of the oldest public UNIX systems still running, SDF, which was created in 1987 as a BBS for discussing anime. And you can find old Usenet posts that are indistinguishable from modern anime shitposting save for the specific series they discuss. As for SICP, it always had a sort of cult status in the CS community so it was perhaps inevitable that it got mixed into that, but I imagine Serial Experiments Lain threw some fuel on the fire with its references to MIT hacker culture including Lisp and SICP.
However, the most direct antecedent of the unscientific and ultimately destructive obsession with Scheme/SICP has to be the old /prog/, which took the extant reverence for SICP and memed the hell out of it. I was a latecomer there so I only experienced it when it was already beset with spammers, but my impression was that while many of its members did watch anime, it actually had more crossboarders shared with /jp/ than with /a/, which is why a lot of the SICP memes are not actually anime but Touhou, such as the "Abelson Stole the Precious Course" video linked to at the front page of this site or https://www.youtube.com/watch?v=aHk42kDwesM. That obsession naturally spilled over into /g/ as well and got caught up in that board's stronger anime influence and imageboard culture so that nowadays you see a lot of pictures of anime girls holding SICP or whatever, but in the end /g/ does not care much about Lisp and its SICP memeing feels superficial at best.