This is all true, but I think the issue is upstream of where you're pointing - democracy declines when the goal becomes to win rather than to serve the constituents. Parties are a way to win and they also reinforce the idea that winning is the goal.

I'm not sure as to solutions but I don't think they're impossible - something like an inoculation of the entire political class against the memeset that prioritizes winning over serving the constituents. Then if an unofficial party tries to seize power in a system that officially disallows them, the majority is already primed to respond in an organized way.