I don't think you understood. You can still get a feature complete social experience that is NOT ISOLATED from anyone.
Your GitHub Enterprise comparison is wrong, because with an onprem github entreprise you don't have the social github features (and that's the whole point of tangled, use something else if you want a private forge for your company, it's not for this purpose)
My point is, Tangled being on ATProto, you can still access all of the repos, PRs and issues of other people by looking through your self-hosted appview even if the official appview is down, because an appview, is just that, an "app *view*" It's the view layer in your traditional app, and ATProto is the database.
It's a view of the data on the ATProto network, it is not the data holder, everyone can be their own data holder that is visible through any appview.
> downtime and self-hosting is not a reason most people are convinced to move forges, it takes a lot to get someone there
Yes, I agree, but I personally think tangled is great because of the interoperability
People on codeberg, on gitlab, on github, on self-hosted gitea instances, on self hosted gitlab instances, and so on, all control their issues, PRs, and git repos (they run on their own infra) but they are also more independent, are not subject to a central platform's policies (or are subject to the one they prefer) and so on, and they also introduce contributor friction, you need separate accounts, it can be difficult to cross reference issues and PRs accross projects on different forges, users can't easily have a central feed of project they starred.
On tangled you get to have the first part (freedom) while not having the second downside (unique account, cross-references work seamlessly, etc...)
Give me reasons open source projects moved forges away from github, and I am pretty sure if tangled did exist when they did so it would fit more boxes of "why they left" than their target forge.