Porn is often really high traffic, which is expensive to run. But a lot of people are weirdos too and tend to push it to the border of legality, which can be challenging for admins if your users keep posting lolis even if it’s not allowed. And they’ll scream at you “it’s not technically illegal”.

The other thing people do a lot with porn is post stuff from sketchy sources or repost paid content for free stealing from OnlyFans pages and the big porn studios. And lately, AI generated porn of non-consenting celebrities. And of course now the increasing pressure to make sure to keep minors out or heaven forbid they’re shown trans porn.

It’s expensive to store all that porn, it’s insanely expensive to distribute it, you need lawyers on standby for the firehose of DMCA reports, you need a solid team of moderators scrubbing the site as fast as possible for CSAM, or run AI tools that needs a lot of fast hardware to run at any decent speed (you need to analyze every frame of a video, for example).

It’s just expensive as removed overall and that’s why a lot of the porn sites have the sketchiest ads ever, and that’s because you can’t run regular ads as most advertisers don’t want to be shown next to questionable content.

On the fediverse you have the added challenge that ideally, you scrub things before they get federated due to federation bugs. Or you risk being defederated which you probably will anyway as most admins just don’t want to deal with it.