The thing with PayPal is that it always seemed primarily targeted towards customer-business interactions. Trivial payments between friends didn't seem like a high-priority usecase back in ~2012. I noticed the same issues as you when I tried to Google its mobile history.

Venmo definitely won the first-to-market/network effect game. That said, I'm not complaining. Unless it looks like they are on course for bankruptcy or there is a major data leak, it's CX is pretty much exactly what I want it to be. The only unnecessary part is the social feed, but that has absolutely no impact on me unless I want it to (and sometimes it's amusing to see the messages my friends attach to them if I happen to look at it).