They exists since I remember myself playing a few years ago, but they weren't so bad...running away from combat using waypoints is not really that bad nor important
But with the mounts its different because you explore the area you're already in and its also getting more annoying with every foe forcing you into combat whether you want to fight or not.
I think its very annoying we can't explore the maps without being forced to stop by that random harpie shooting an arrow at us to kill it, or being hit by a gas or a trap ,or worst when it get glitched and no matter how far you try to talk away from it you are still in combat.
Imo we should be able to mount while in combat, the mounts are not busy while we mount/dismout all day long but when we get hit by random foes suddenly they feel the need to disappear instead when we need them the most.
I see no logic in this.
Of course they should not remove foes ability to dismount us and if they were to dismount us we should have a cooldown instead for maybe 5 seconds until we can mount again.