Standardizing on one single tiny little project is always a bad idea. Why? Some examples (which are admittedly not related to postgres, because I don't know their structure):

1) A single person, doing a ton of heavy lifting, leaves, or worse, turns it over, or silently sells out to a nefarious person.

2) A severe security vulnerability is found. If everyone is using postgres, everyone is vulnerable. Bonus points if the vulnerability is either not publicly disclosed or it is hard to fix.

3) Commercial/Government interests heavily influence and push the project into places that could make it vulnerable in any given way. This is absolutely a thing.

4) AI. No clarification here. Just use your imagination, with recent news regarding FFMPEG and other projects in mind.