I went many times in the PvP zones, I have seen few players there, got in a fight with one of them and it ended with no kill.
Back in the D2 days, PvPers was using glitch in order to PvP, Teleport was not mandatory but highly recommended.
D3 has the “Brawling” option that I used 2 or 3 times, boring as hell because the 1st to get it die…
PvP has a better tuning in D4 and yet, almost nothing happens in those areas. There’s no carrot on the stick beside cosmetics and I think that this is the reason.