It's funny, I've been around the 16mm reels provided to Funimation for a long time. The first time they transferred to SD DigiBeta tapes I was an assistant editor at the post house doing the transfers. Those transfers were used to make the NTSC broadcast masters. Eventually, they started making DVDs. By that time, I was at a different company that was hired to program the DVDs before eventually working directly at Funi. While I was there, they decided to go back to the film prints for a new transfer, but some very questionable decisions were made during that transfer. When the box set was released, the fans hated it. They went back to those prints a third time for a new transfer with a more sane approach. The colorist found reference film for the stock the prints were on, and had the closest color the creator had seen. After some years later, I was working directly with that colorist. We talked a bit about that film. He was flabbergasted about the fans. Someone on the internet looked him up and reached out to him with less than favorable things to say. That's when he learned about anime fans. While I was at Funi, we had arguments with fans that didn't believe we had the film to do these transfers. They were adamant that we took the original DigiBeta tapes, yet not questioning the origin of those tapes. Posting replies with people holding the film reels did nothing to dissuade them. Funi went so far to include an extras on the Blu-ray release of the process of the film transfers, the frame-by-frame restoration process, and other steps. Fans were still online saying they could do better. I wish them luck.

I'd caution not to lump all fans together as a single group. The internet in general (or perhaps more accurately the world as a whole) has plenty of absolutely awful people with seemingly nothing better to do than pointlessly harass others.

Anime fans can be a bit ridiculous but at the same time some of them accomplish impressive things. They've pushed AV1 (and other) encoders forward substantially. A number of older shows that were never going to get a remaster have been made much more pleasant to watch thanks to downright obsessive restoration efforts. They've also salvaged at least a few horrendous remasters that would otherwise have never been fixed.

Amusingly they're responsible for the propagation of the leaked DCP versions of several titles despite the fact that even most fairly high end devices aren't capable of playing such videos back due to the hardware being insufficient.

I still find it hilarious that of all things people pirating cartoons in their free time ended up driving a significant amount of codec tooling development. I wonder how you'd calculate the broader net economic impact of such an outcome.