You are right. The key is to find a structural solution to this, since this is a common occurrence (i.e. joining startups early stage) - and spread information about the "best practice" way of avoiding situations like the one I went through.
Anyway, there is a solution to this - it's to develop a personal set of red flags and heuristics that you use to weed out bad founders when you talk to them. I have one, and it disqualifies probably 95% of startups that I talk to. Unfortunately, I'm not sure there's any way to build this reliably short of bitter experience. The problem with a general "post your grievances" board is that you don't get both sides of the story. I know at least one person who has posted their grievances publicly on HN where I personally witnessed what actually went down, and their account is nowhere close to what I witnessed.