You're basically describing TAI (International atomic time). UTC is just TAI with leap seconds applied, as I understand it mostly for political reasons (it was easier to get everyone to use atomic time if it's at most a 0.9 seconds off from the observational method used before).
We also have GPS time, which is TAI minus 19 seconds, which is probably the most "popular" monotonic time standard we have on the back of, well, GPS. Lots of choices!
Pretty much, yes, or a new standard which is regular that solves the unpredictability problem of leap seconds, as well as the "time actually doesn't work like almost everyone on the planet thinks it does"-problem.
https://en.m.wikipedia.org/wiki/International_Atomic_Time