Maybe people might not agree but I think Simply Plural can pose a threat to those with CDDs. Not always a huge one. I'm sure some can use it and see benefits with functionality, but some are at higher risk for being harmed by it. Especially if you have more alters than most (like 20+), aren't in treatment, and are mainly concerned with the social aspect (sharing it with friends or even just like any other social media).
I personally am concerned because:
More alters=more dissociation=more flooding as co-consciousness, communication, and awareness of other parts is increased. if you're logging 50, 200, 600 alters and not in trauma therapy, this is dangerous. Full stop.
If you're not in treatment, tracking symptoms like amnesia and leaving notes like reminders is fine! But mapping things like patterns, relationships, histories, etc can be risky.
It can promote elaboration on parts that are fragments or less elaborated before they are ready. They don't need to instantly be logged.
It is often used unsafely online and promoted to strangers detailing histories, relationships, and traits of even very vulnerable alters. Like showing child alters, we don't need to know about them. If someone wants to hurt you, you're handing them a damn good weapon to do it with.
It can be very confusing for some alters. Confusion towards alters showing up and making profiles is often portrayed like a silly minor thing like "oh damn who are you? Guys is that Dream?!" but if it's not Dream and it's an introject of your abuser and you have a 12 year old alter who does not remember the abuse and thinks they were not abusive to protect themselves, and they see that? That could be dangerous.
It can also cause curiosity that doesn't feel dangerous. "Oh we have an introject of that guy?" "oh she looks like our old childhood friend I should talk to her" "i wonder if we should try and be friends with this guy, he sounds friendly". Then you're breaking down walls that can threaten everyone's stability without professional advice.
Exploration and exposure like this can be largely disruptive and it's covert for a reason. This is especially unsafe if you are not in a safe home environment.
I think that there is social reinforcement and incentive to use tools like this believing it is completely safe for anyone with a CDD. You see everyone else with one, why would you making one be an issue? They're all sharing it so they can know each others systems better so shouldn't you too? Looks fun, maybe helpful for friends? But it can definitely create problems that don't feel apparent on the surface.
There's definitely more but if you're gonna use it, just use it as responsibly as you can and keep safety in mind. In therapy, logging and mapping normally comes later on as trauma therapy is being worked through. It's not by any means recommended early on aside from possibly basic things to keep track for functional reasons rather than, just because you want them all logged.
Just, don't call it a disability aid. It's not one.