What do you think of escort missions?
Everyone knows to avoid making them by now basically because it’s irritating to make mission completion dependent on an entity which you have no control over. Like you can’t realistically make this other entity avoid damage. This is more a matter of technology and user perception than an actual mechanical issue with the concept of escort missions. The issue is that players don’t feel a strong connection between their decisions and outcomes.
The annoyance of escort missions is mitigated as the behavior of the entity to be protected is more consistent and predictable. Escorting something that moves on a totally fixed and unchanging path is usually less aggravating than other possible cases, where the escorted target can wander off on its own, get stuck on geometry, engage enemies it should avoid and get itself killed, etc.
Also irritating is if you’re not allowed to move too far ahead of your escorted target, and generally if it does a shitty job keeping up with you. Emil is like this in that one isometric dungeon in Nier. Many games mitigate this by teleporting the escort to you if you’re too far ahead, though this can sidestep the point of an escort mission.
The abstract idea behind the escort mission makes sense, target separate from you that can take damage, it pairs up with a lot of story concepts, like protecting things, fighting alongside a buddy, etc, it just usually doesn’t work out for an assortment of technical reasons, or poorly considered design.
This page lists a bunch of examples, and happens to be nice enough to categorize them by what’s annoying about that particular escort mission.