That's a good point but I suspect the feasibility of this approach depends on having large facilities and uranium procurement operations. These are things that can be regulated. You can see this in the Iran situation where their "breakout time" is measurable. With nations willing to negotiate, this could be brought under control. However, tbh I think they probably should have a deterrent as they are facing a serious invasion threat by nuclear armed powers. The world needs to scale down in tandem, not weaker parties first and stronger parties later.

not just fast manufacture times but replace many smaller yeild weapons but newer high yield weapons to keep the numbers in the agreed range but not actually reducing your damage potential.