The very first PMFs were introduced only a few months after people had figured out that the BGS could be intentionally manipulated at all. Obviously there weren't individual steamroller factions before then - there hadn't been sufficient time to push any individual faction beyond a few systems present - but people had certainly expanded adopted factions to noticeable sizes.And I don't think you need an alternate universe to prove this, just look at the game before PMFs came along. There weren't a few factions steamrolling across the bubble like a few PMFs are doing now.
The main cause of the steamroller for both PMFs and adopted factions is the BGS changes in 3.3 - by preventing states interfering with each other and allowing systems owned by the same faction to behave independently, Frontier sorted out some background problems with very large factions ... at the cost of allowing them to get even larger even faster.
That would be effectively equivalent to ending new PMF placement, since people would just use spare alt accounts to claim factions in the remaining systems.At the very least, expand the PMF rules such that systems where a supported faction is present are also considered invalid targets for placing a PMF, since the intent of that rule is to prevent new groups from plopping their new faction on top of someone else's home.