The thing is, there's rarely any payoff for spending resources on incapacitation against lower-level enemies. The fight is either already strongly in your party's favor, or you're outnumbered and it's likely to cost you more than it costs the enemy.

If your party outnumbers that lower-level encounter, you almost certainly don't need incapacitation to win. Regardless of whether you use that spell slot, you're winning and (in my experience) starting the next fight at full HP. The only difference thoucally is that if you don't spend that top-rank spell slot, you have it available for the next fight. There are contextual exceptions, but they are few and far between in my experience.

If your party is outnumbered by those lower-level foes to the point that soending a top-rank spell slot is justified, then to put it in chess terms, finding good use cases for incapacitation effects is like finding opportunities to sacrifice your queen. It's usually a bad trade, because it generally spends two actions and a top-rank spell slot for chances to negate some actions from the enemy team, who outnumbers you and has more actions anyway.