There are good reasons mentioned already, but additionally, there’s a real strong cargo cult developing around Postgres these days.
That’s the part that baffles me. You’ve selected a DB with native support for esoteric but useful data types like INET (stop storing IP addresses as strings in dotted quad!), and a whole host of index types beyond B+tree, but they’re never using them.
Read your RDBMS docs, people. They’re full of interesting tidbits.
"Every single one" in your team agreeing on a single specific technological choice is one of the rarest things I can image! Developers argue about libraries, frameworks, programming languages, services, etc., and I think it speaks for itself if Postgres is the thing that comes closest in bridging the gap at least on one layer in the tech stack. Postgres is a "conservative" choice with a very active community and extensible ecosystem.
Also, nobody is ever making use of their technological choice to its full extent, you'd rarely know what you'll need beforehand, and it's just nice not having to add other storage engines when that one feature request steps into your life.