I actually don't see how this nerfs the off tanks aka dive comp, if anything that gets encouraged.

The major flaw of Horizon was that it lacked a strong choke for A and barely any defense for defenders on B in exchange for an extremely close spawn.

And while they kinda fixed the latter, the former stays unadressed, and their "solution" was to put high ground hard covered areas everywhere - which encourage heroes with strong highground play (Widow, Soldier, [McCree]) which in turn get countered by getting dove.

If they want to make the shield tanks more viable there need to be 2 things: Extremely narrow chokes, walls and ledges. Orisa and Rein have no reason to get picked if they can neither slam people into walls or off the map, and don't need their shield because you can just dive over/around every chokepoint. Now Horizon still has no convenient walls, no ledges, the low grav area is as irrelevant as ever, marking no reason for the shield tanks to get played ,unless you're in gold/plat and play bastion orisa on defense A.