Social media currently is mostly based on people using a central “intermediary,” like a website or a mobile app, which is run by a third party. If you aren’t using that same intermediary, you can’t communicate with others.
In this system, the intermediary has complete control over your communication. It can set whatever policies it wants about what you can post, and it can shut down at any time, taking your posts with it.
Tumblr’s policy change is a prime example of how that control becomes a problem. Since 2018 December 17, Tumblr forbids many forms of adult content, and it has made pre-existing adult content nearly impossible to access.
Running my own site gives me more control over what I post. Plus, it’s much easier to move the data elsewhere if I need to.
I’ve said more than enough already. This is a site for sharing porn, for crying out loud! Other people have been talking about this and trying to come up with solutions. But none of it is going to be quick or easy.
For now, here’s something I recommend: Back up your stuff!
If you’re an artist or any sort of creative person, make sure you keep your own copy of what you post. This way, you can reupload the highest-quality original somewhere else if you need to. (And keep in mind that having backups is a good idea for digital data in general.)
And if you have the skills, consider running your own site. ;D