The reason it works so well for DAO, is the fact that Bioware created their combat and skill system from the ground up, for RTwP.
Translating tabletop DnD rules of any edition just doesn't work well since in every version, there are mechanics that rely on a TB system to be implemented properly.
Yup creating a system specifically for RtwP definitely helped. But it's not impossible to create such a system for D&D, depending on the how strictly you care about the implementation. The RtwP systems work pretty well for P:Km and BG1&2 (though I greatly prefer P:Km's TB).
The biggest problem with implementing RtwP for 5e is probably reactions but tactics would address this: giving a priority and conditions for casting Shield, making an AoO, hellish rebuking, imposing disadvantage via Protection fighting style, etc. Actually, it'd be great if BG3 had such a system for reactions instead of toggle.
For 5e RAW, bonus actions are fairly rare which would help simplify the tactics. Having 10 tactics slots for each character-especially martial characters-would probably be sufficient to cover most fights. Pathfinder might be more difficult because you have swift actions, move-equivalent actions, and standard vs full round actions.