What you're saying sounds reasonable but I think it is completely wrong.
I strongly believe that startups very rarely fail because they have chosen to build on a particular immature technology. Some fail or stall because they cannot bring themselves to stop redesigning and rebuilding on the next new technology or design philosophy every couple of months.
But these are completely different issues (related by psychology for sure but not by necessity)
My opinion is you should choose what you find coolest and most exciting now and then stick with it!
Of course the technology you choose should have some traction but don't choose technologies of the past! Whatever you choose will be the past soon enough and that is when you must find the strength to stick with it and get on with creating value for users.
I don't think his comment says that they failed because they chose the wrong trendy language. They are failing because they are too concerned about the language and the process rather than the result.
While I don't really agree, I do think that if one intends to work on a side project or a bootstrapped company, they need to do it in a way that is somewhat enjoyable for them.
It requires lots of energy to see these projects through, and it's hard to emit that energy on something that you don't enjoy doing. If using a less common technology is going to get you working on the problem enough to start getting some velocity, that may well be a worthwhile tradeoff (as long as it's not too out there).
The other thing to consider is that while a basic library supplied by a young language may suit your needs when you're starting out, larger ecosystems are likely to have more advanced libraries that have better performance characteristics, support more obscure use cases, etc., which will only become more valuable as one grows.
I strongly believe that startups very rarely fail because they have chosen to build on a particular immature technology. Some fail or stall because they cannot bring themselves to stop redesigning and rebuilding on the next new technology or design philosophy every couple of months.
But these are completely different issues (related by psychology for sure but not by necessity)
My opinion is you should choose what you find coolest and most exciting now and then stick with it!
Of course the technology you choose should have some traction but don't choose technologies of the past! Whatever you choose will be the past soon enough and that is when you must find the strength to stick with it and get on with creating value for users.