Goldman has done this for decades, pushing it even further by having developed their own language (Slang), graph db (SecDB), and IDE (SecView). Many engineers resist working it in, but for any strat it's mandatory.
They continued with their own db for decades out of inertia and also it worked fine. I think they've long since switched to TCP/IP and the public internet (for a time there was a Bloomberg network parallel to the public internet).
I would never want to work for a place like Goldman anyway, but knowing they had their own idiosyncratic tech environment would certainly be an additional negative.
One of the people I regard as the Godfather/OG strat is Emanuel Derman (https://emanuelderman.com/). Another transformative (in my time) person in the Strat complex was Marty Chavez (https://www.rmartinchavez.com/). Both amazing people on and off the trading floor.