Most successful startups were able to make the thing that they wanted to make, as a startup, with existing tech. It might have a limited market that was expected to become less limited (a web app in 1996, say), but it was possible to make the thing.

This idea of “we’re a startup; we can’t actually make anything useful now, but once the tech we use becomes magic any day now we might be able to make something!” is basically a new phenomenon.