Not entirely sure if this was what you were getting at, but I've always found advice against 50/50 equity to likely be the product of a cognitive error. People

Not entirely sure if this was what you were getting at, but I've always found advice against 50/50 equity to likely be the product of a cognitive error. People see companies with 50/50 equity splits failing due to founder disputes and extrapolate that to mean that 50/50 equity split is sub-optimal. This does not necessarily follow - it could very well be the case that it is the cause of disputes but that it is still often the best option. Sort of like how there's a lot of problems with democracy but the prevailing wisdom is that it's still the best form of government out there (same with capitalism). Not saying that it necessarily is the best way to do things (though I'm partial to it), just that I have not seen convincing arguments against it - that it doesn't work sometimes does not cut it, it has to work less well than an alternative.