Hives are imbal because they are used to spam boys. You justify the increase in infrastructure to spam up RAS SCUs in a singular, defensible location where the hives can either protect thru shield assist, immediately put infinite eco into eco production, or deal with a threat by making a t4 quickly.
Remove SACU garbage and hives are back to their normal stationary use as stationary buildpower that can't help you build up eco since you need to spread out your mass fabs and can't cover them with a singular shield.
And you do get different results based on games you look at. I'd say you could pretty quickly see SMLs are quite OP by looking at turtle games (as this thread is all about it). You would also see that scathis is a garbage T4 by watching dual gap games. In fact, novax would even be considered trash-tier in a dual gap game. These are all not true at all on maps that allow for interaction at all or most phases of the game.
Ultimately balance, or determining if something is OP or UP, should revolve around looking at a game state where you not only had to take into account the opportunity cost of getting to a position but then the utility from using the option.
In dual gap games, this is drastically simplified. You have your eco slot make the first and really final decision "Do I nuke rush or do I eco sim into t3 arty or t4 game ender?" and this is in just about every situation what decides the game assuming enemy air is not extremely competent against your garbage air.
There is no decision "hmmm maybe I need to make a T4 to help win mid" or "hmmm maybe I need to put more mass into air production" or "hmmm maybe I need to get into navy" because the map is extremely linear with 1-3 things to think about for really any slot. If your map is reduced to this, it doesn't really tell anything noteworthy about the state of balance in the game.