Some questions I have as someone who isn't a system

Serious questions:

1. why do some people think endogenic systems are invalid?? From my understanding its just having DID without trauma, maybe theres something deeper I'm not seeing because usually I can see how someone can interpret something as bad but idk man.
2. If anyone has the time, could someone explain what types of alters there are? I understand fictives, ocs that turn into alters sometimes, the simple things from a friend of mine but not much.

Silly-ish questions:

1. What's the weirdest argument/interaction you/someone else has had with another alter?(if that makes sense)
2. Do any of your/someone else's alters have different feelings/preferences on things or is it like a collective "we like this thing/we dont like this thing"