"nonlogical responses"
Clearly I'm not communicating well.
Let me re-start by saying, I hear what you're saying. And yes, I too have experienced situations where teammates flake out and zip away. Usually to their swift and ugly death. It's sad.
But what it also is: the player using the tools provided by the developer for the expression of his or her free will.
If you want "good " teammates, and by "good" I assume you mean teammates who are more likely to share your play style and match goals, then the place for you is ranked. Just as quitters annoy you, the only thing I can suggest is that you go where the quitters aren't: ranked. If you want teammates who don't abandon you (and notice how polite I'm being by refraining from any suggestion that you may be one of those players who is given to doing things that deserve abandonment) then you need to play ranked. Then it won't matter if the zip lines go or stay.
But for the record, they're going to stay no matter what. Dev put 'em there for a reason. And it wasn't just to annoy you.
For the sake or argument: Do they need to delete tridents from Storm Point for the same reason? Do they need to delete jump towers from Kings Canyon for the same reason? Do they need to nerf Octane's sprint or Valk's ultimate because they can be used to "run away" or "abandon the squad?" Does the dev need to add a mechanic where teammates who wander too far from their jump master start to lose shields or health? I know this all sounds like I'm being difficult, but these are intended as honest questions. I've actually put the "no wander" mechanic out there before, and I'm more than a little surprised that Respawn hasn't done something like it. Yet.