the problem with this is that when you're a country that has 0 mic at start, researching and producing two different tank lines uses up 66% of your industry and it's impossible to produce all of guns/arty/support equipment/aa as well.
in fact, even if you start with mic and factory dupe civil war, you still won't have enough stuff from buying alone.
it's simply not an option for truly destitute nations. takes too long to make the divisions, and too long before getting into and winning 1st war. you don't have 10-11 military factories as many of these nations...you have 3-5. the best way to change that is to win wars, and that means winning with some combination of infantry kits, support arty, and maybe some support equipment. which is doable with good enough micro.
saying breakthrough will "never be high enough to do anything" makes no sense. it's a literally false statement; the only time adding breakthrough ever does nothing is when you have *already have enough* to match all incoming attacks.
infantry + support divisions can take you quite far: