In this case the benefit would be:

- your data lives in one place, your Personal Data Server (PDS). You can self-host this if you like - The AppView (in this case, tangled.org) aggregates the data from many PDS's into one view. - If tangled.org enshittifies, you can do all the same things from any other AppView -- tangled.org itself is not privileged in any way.

Social logins on independent forges help, but personally I'd rather have a single account to manage -- and the AT protocol means that any individual forge can go down, but the data remains accessible from other AppViews.