Yes you need an account from the specific Mastodon instance to post on that Mastodon instance.

That was a Lemmy comment, but my mastadon post goes to all mastodon instances, regardless of region. Filtering or subscription is by hashtag or user. I do not get region-locked by my server to make a post, to read a post, to interact with a post.

But anyways, that is besides the point. A classified listing is by design lioation specific. All your argument seems to boil down to is that you are annoyed that you don’t have centralized accounts to log into different classified pages 🤷

No, that is not my complaint.

I, as a user, cannot use this solution. I have no way to use it, as a user, because the server determines region, not the user. I, as a user, have no way to interact with flohmarkt or my local or regional community, for reasons of a design decision that is not relevant in any way to a user or a listing.

I, as a user, can’t use flohmarkt, because the design of it does not allow me to. An arbitrary, unnecessary, forced limitation. Simple as that.