So what's actually the idea behind certain parties allowing capitalists to open factories, but not allowing them to expand them? Is there some real world equivalent to that or has it some in game function? It doesn't really make any sense to me. More than once I've wondered why there wasn't any industrial growth, only to find out i've got some destructive party in charge.
Capitalists are not restricted by any economic ideology other than Planned Economy (and my memory is fuzzy on that). However, factories and their upgrades do cost more the further one gets from Laissez Faire, which hinders capitalists, but does not stop them.
Capitalists at least in state capitalism, tend to almost never expand factories, if ever. They will try and build new ones though. It's possible it's a bug, it's possible it's just WAD and not really obvious what's happening (it makes sense that the upgrades cost more, it's possible the upgrades for cap's aren't being properly modified by costs, or they just become stupid when under state capitalism or interventionist). Unfortunately, when you have 100k unemployed pops in a state with 8 factories waiting to expand they'll go build a new factory in one with only 25% of the jobs filled.