Shadowbane, Jumpgate, LoTRO though the latter artificially segregated PvP.
I've never played WoW or ESO, but your personal assessment of whatever PvP changes you believe adversely affected PvE content does not in any way imply that PvP balance changes must do so. What you know about this is impossible to falsify and thus impossible to demonstrate. A million examples, even if we completely agreed on them, would still only need a single example to the contrary to demonstrate that PvP changes do not need to negatively impact PvE gameplay.
Regardless, I'm not fond of games that don't look at overarching balance holistically. As far as I am concerned, NPCs and PCs should all be playing by the same underlying rules, while the mechanisms underpinning the setting should be self-balancing. Very few games live up to this, but not because of any PvP/PvE dichotomy.
As far as I am concerned, if a game needs separate PvP and PvE rules, something is seriously wrong with the PvE aspects of the game. As one might imagine, I am not a fan of most themepark MMOs (which are mostly only MMOs as a pretext to be online only and extract a subscription fee or microtransactions).
If the two modes (PVP and PVE) are together it never works.
Example: WOW at the beginning was never intended as PvP, yes you could do it but skills/talents etc were solely designed for PVE where class designers were free to base skills on the way they wanted a character to 'feel' and its role within the game.
Go back to the first great MMO, Everquest, designed around the holy principles of group/raid PVE, the Tank was hard as nails, the healer could just spam and the wizzys had nukes that were just ridiculous.
WOW designers bought into this because they intended the game to be a PVE dungeon/raid game so Priests were top healers, warriors damage, Pallys meat shields etc.
Now take that into PvP, how is a Priest going to kill a Tank? Spam it to death with some rubbish excuse for an offensive spell?
The biggy was Soul Link on Warlocks (my class), we were designed to do crowd control, SL kept us alive by transferring damage to our pet, PvP wise we were unkillable.
At the start it was Open world (opt in toggle) PVP, it was fun but eventually all you had was a million undead rogues since nowt could touch them.
PvPers complained, whined and in came the nerf bats.
All those really decent skills that could save a raid were gone, deemed OP by the PvP community.
Eventually they ruined what class mechanics existed.
WOW had to reset, it made battle grounds but the damage was already done.
They made pure PvP servers with new rulesets but they were Ghost towns.
ESO a game where i was full time PvPer, kept it separate in a large Open battle zone but they couldn't sort out how some of the spell system worked (in PVE classes overlapped spells to create powerful attacks) so that got nerfed.
Eventually they cut staff so both modes sort of melted into each other with future 'balancing' and skill progression watered down so as not to effect PvP.
This made what extra PVE content they made difficult.
Another example where i was mainly a PvPer was GW2, some AOE spells were really cool in PVE but in battlegrounds 'ball groups' had multiple classes spamming these spells and just running around near unkillable, it was a joke.
Shoot me because i was one of those that worked out exact timings of multiple players casting said spells to get maximum effect, you want to win right?
Nerf bat time, spells ruined for any PVE.
If you want PvP the game has to be based on that from the start, weapons balanced, skills with counter skills, a level playing field.
Those games are almost always FPS.
PVP balancing in PVE always restricts freedom and fun to play how you want, don't be fooled by ESOs and class any weapon advertising, in PvP there's a meta and its boring.
But if you want to reach the top spots that's how its done.
O7