This is an interesting feature. Recently I completed a migration tool that merges all the existing teams into a single team. We were finding it difficult and pretty much non-collaborative to use multiple accounts across different teams.
I posted the basic code that manipulates the database here - https://github.com/vrenjith/matter-merge-teams
(This works in the scenario I have tested, while there are some issues still around the direct message migration which I am kind of ignoring for the time being)