It is not exactly a limiter, you can think of it as increasing enemy defense. Of course, I cant go into details with how it would feel. Tbh, my intention with this idea is more about difficulty anyway and not to keep the steep progression curve. So yeah, upgrades could propably feel different in Torment 3 and 4.
My change is basically intended to give enemys a real chance to hit back if a player decides to step into a more difficult world. There it would make a lot of difference if an enemy dies after 3 hits instead of 2. For that to make sense I linked my original suggestion that also suggests to tune enemy attacks.
My personal impression with current D4 is that growth in power is not feelable within our tier system, or at least not for long. There is a Torment number, a Pit number or some combat text numbers that most players use as indicator of progression, which is fine, but it has nothing to do with difficulty.
Thats essentially where this idea came from.