I'll try to put it simply, and to explain my reasoning behind not wanting them around :] This isn't a syscource blog, so I'm not gonna try to like debunk things, I just wanna explain why they aren't allowed here specifically.
Endos, or Endogenic Systems, are systems that believe they are plural for any reason that isn't created from trauma.
More specifically, they claim to have disorders that require trauma to form (DID, OSDD, PTSD, UDD, etc) without having trauma.
Usually, people who identify as endos are:
‿ Systems who do not remember their trauma (which is completely valid, but by claiming they are endo they are spreading misinformation and further harming themselves)
‿ Singlets (people without said disorders at all) misdiagnosing themselves (which is yet again very valid, but usually they refuse to believe that it could possibly be a different thing that they haven't looked into yet)
‿ Singlets who do not have any disorder at all who simply want to be a system because they think it is fun or interesting (see: ableist, god forbid).
Generally (although obviously not all, but a good portion) tend to put down traumagenic (systems created by trauma) experiences and their opinions when they don't match up with theirs, harass and fake claim traumagenic systems, spread misinformation, and generally create a very toxic space (there are many horror stories of trauma-genic systems in endo-inclusive spaces believing they are endo after being told that their trauma was fake, or that they shouldn't look into actual medical professionals). Obviously, this isn't to say every traumagenic space is completely free of any assholes and that we're all angels- there's many examples of traumagenic systems harassing endos, too. Generally though, it's closer to like a 10-1 ratio from what I've seen. We may be biased because we don't partake in any endo spaces anymore, but even when we previously did it was a horrible stressful experience.
I don't care if you do support endos or not, it isn't any of my business (although personally as a traumagenic system who has been repeatedly put down by endos, we do not support them and do not want them anywhere near us).
I hope this helps, and you have a great day! If you need anything else clarified I would be happy to explain further, although we aren't open to debating with endos over our or their existences.