@petros Well, the example from the OP is about account migration, which doesn't even exist on other platforms, so it's clearly in the first category.
There are a good number of things that just don't make sense for normal social media use. e.g. If I reply to a followers-only post, only *my* followers (and named people) can see my reply. Anyone trying to follow the wider conversation with limited follows can't. This exposes the internal model at the cost of usefulness.
@petros Having said all that, emulating the before is... complicated.
There's value there - e.g. we've got posts, boosts, likes and bookmarks. Copying's not all bad - many features are the result of built-up experience that we shouldn't ignore. Just understand the feature first.
The other side is that if you build something that looks suspiciously like a feature that exists on another platform *but behaves subtly differently* you're going to break expectations and make people sad.