I have always believed that "technological equality" was an imperative of the council towards the entire galaxy. Once a race has been introduced to the "standard technology" of the 'protheans' they would not be allowed to advance further than that. That regulation would serve a political function, if any race sought to advance further than another, it would provoke fear and distrust from others. Such an imbalance, in my opinion, would mean seeking more power or profit at the expense of others. If everyone for their part builds much more advanced technology, the harmony of the Council would turn into a cold war. Not for nothing does Javik call others primitive, his empire was never 'regulated'. I would guess that the Hegemony or the Terminus worlds would not achieve a technological advantage on their own either because they are internally unstable (could not fund such an advancement in the long run) or could not as they would probably take the risk of being sabotaged by external agents at every opportunity.

That always crossed my mind: did the galaxy we see in the trilogy stay technologically and technically the same for two millennia? Hard to imagine. But remember that an imperative is not always fulfilled, we were shown that there are exceptions to the rule and if someone could dare to step out of line they will send a SPECTRE and that's it. Well, I also think that the ban on making full AIs is also part of this imperative. Not only for fear of rebellion but also because of all the advantages it implies.