The porn would be on it’s own instance not federated with the common Lemmy servers. So it wouldn’t show up in /all.

Those who want porn would have to actively seek it out by connecting to those instances. More over, if one instance starts allowing unacceptable material, the other instances can blacklist it.

edit: I was wrong. Lemmynsfw is indeed federated.

The question isn’t “do we want Reddit users who want porn here?”, but rather “do we want Reddit users who see no value in a space unless it’s full of porn?”.

There should absolute be spaces for sex workers, both online and in meatspace, but maybe the produce aisle still has value even if it’s not surrounded by strippers. And maybe. People want to buy produce sometimes without seeing said strippers.

Now, whether there should be instances that are all sex workers or not is a different, and complicated, question. Sex work is often criminalized, and even the legal forms of it are highly scrutinized. Putting them all in a confined space makes it really easy for authorities who are looking to send a message to unilaterally shut down their infrastructure. We’ve seen it on the Fediverse before. They need some kind of smoke screen in order to be protected from the Delores Umbridges of the world. But that doesn’t mean people who are unable or unwilling to handle the added stress and responsibility needtl to be the ones doing the screening.

The point of Reddit, and now Lemmy by extension, is a sort of link aggregator + comments. As with all content: sure, general sites all exist for that porn, but sometimes if you want more specific categories it’s a lot easier to have community collected content that is sorted.

If someone wishes to spin up an instance for it, so be it. You are welcome to ignore it and not federate with it. That’s the point of the fediverse.

it would take quite a lot of server resources since it’s all images and video

Instance rules could mandate media to be hosted externally. Imgur is out of the question but plenty other services exist.