I think you're still missing tsally's point. He pointed out those projects because they required the original implementer to advocate them. His point was not that they would make good investments, but that they probably would not succeed on technical merit alone; they required someone who understand their technical contribution to advertise them to others.

I think your second point is off, too. Your argument is that startups usually fail for non-technical reasons, and I agree. But that's what tsally was trying to say: it's a rare person who can smell-out good technical work, understand it, and realize it's contribution. This is the sort of person you'd want to have as an adviser when it comes time to determine a business model or how to advertise.