"This could be discussed in purely TOS terms, too - but the thing is, Star Trek nowadays features quite a bit of "bracketing", in which the technologies introduced in TOS and expanded upon in TNG are revealed to have existed in ENT already."
Please forgive, but especially
ENT is retroactive continuity in my personal opinion which I reserve the right to ignore (except "In A Mirror, Darkly" as it conveniently takes place in the Mirror Universe
My whole issue with retroactive continuity, mostly, is the lack of devoted research and effort to be accurate. I've come across websites claiming the "antimatter nacelles" mentioned in TAS to be erroneous, although there's obvious and undeniable evidence in TOS that the warp nacelles do contain matter-antimatter reactors and
Again, bssdwlf's conclusions
to prove the existence of three matter-antimatter reactors aboard the TOS Enterprise
are a state-of-the-art example how to do accurate treknological research, IMHO. It's rather a shame it hadn't been done before.
Applying retroactive continuity to solve a treknological riddle is a valid option, IMHO, but one that comes last and only after a thorough research of the original 'facts' hasn't provided a credible answer.