3. Shove = Action. It is an attack. It is not some minor extra ability. If Shove is a Bonus, one still does not need Disengage. I can shove an enemy 30 feet away and then shoot them or run to high ground or whatever. Why waste an Action to disengage if I can shove and still move and shoot?
Also, D&D is a team based tactical combat system. If a lone archer can both shove a melee attacker away AND shoot them with an arrow on the same turn, you don't even need team mechanics. I'm not sure them folks at Larian understand how to make party based combat fun since they insist on allowing more actions in BG3 that undermine the teamwork. Protecting the archers by shoving away attackers gives melee tanks a purpose. Rogue archers are special because they can Disengage and attack compared to Fighter archers who are otherwise better and tougher but lack that ability.
I wish they would just stop changing the rules. The only changes to 5e that didn't make BG3 a worse game are potions as a BA and Wizards getting access to more cantrips. (It's frustrating you can learn all level 3 spells in the world but can't somehow learn mage 101 like Mage Hand or Light if you picked something else.)