It's pretty trivial to list reasons why you'd
want a local chat app over a US created one.
It is just too difficult to make.
I don't think many people admit how differently we all think about software creation, all the tools that currently exist are shaped 100% around American big tech needs (cool i guess) and the American personality.
It is incredibly difficult to go off-piste and create a different paradigm on computing like Xerox did (which Jobs and Gates 'borrowed from').
The existing eco-system constantly updates/changes itself according to an American clock, so you get isolated and disconnected (from knowledge bases and relationships) if you try to go for a 'long shot'.
Even making small changes have to fit in with the existing eco-system.
99% of all the new ideas that could be made require radically different tooling and that is deeply expensive, constantly contentious with existing powers and disruptive to current services.
Sinply changing Google maps to list street names even when fully zoomed out OR to suggest vocaly three-moves-in-advance when driving.. is basically impossible.
Tech has clamped itself down and has no desire to allow anyone to tinker or tailor their own solutions.
It is deeply deeply frustrating to see what could be made better and to be arbitrarily locked out.