Doesn't really give you an advantage if you don't have customers. Even after you have customers, oftentimes the old/boring technology actually results in a faster, better app.

There are always tradeoffs, though. Using technology X instead of technology Y isn't free; maybe there is an additional up front engineering cost, or maybe it's harder to hire devs who know X, or something else. And it's impossible to generalize, of course, but usually the tradeoffs for using superior tech aren't worth it in the short-/medium-term, which is all that matters as a startup.

I think "opportunity cost" is the phrase for which you're looking.

I don't think you and he are in disagreement. Obviously you should do what will give your business an advantage. He is just saying that it is easy to think that certain new technologies will give you an advantage, but then realize later that what they cost you in bugs/complexity/maintainability etc. make it not worth it for the business. So it's usually better to go with tech that is tried and tested rather than always reaching for the latest new thing.

> and it actually results

Big if there...

new tech & research usually make little business. but are often a win for everyone.