Ah, I agree with your conclusion but not about sharing db's. Sometimes its literally the only way to share data (particularly very large sets of data).
Yep. The only example I have from my career was a team having their own read replica and ETLing that to Hadoop. The schema hadn’t changed in 10+ years, so it wasn’t even considered a real risk.
Somewhat more macro services can make sense, especially when each team owns a service. That’s also when sharing data is harder.