In my company, we hire middle of the pack programmers for a bargain and use commonly known tech stacks.
The customers will not know the difference.
Having done some recruiting at a startup last year, even getting the top 50% to reply to an email is a tough proposition. The problem really stems from brand awareness. No one has heard of your startup, so in a sea of "help wanted" postings on Angelist, Stack Overflow or Craigslist or cold emails, it's extremely easy to be ignored.
Using novel technology and getting the word out (as Twitter and Jet.com did), can at least get technical awareness within a motivated subset of engineers who are interested in said new stuff -- and of all skill levels.
That said, Peter Norvig made a pretty good refutation of your core point[1]. Say your initial site was successfully launched by average engineers. If you're not always trying to hire better than the average employee at your company, your team just gets worse over time.
[1] - https://research.googleblog.com/2006/03/hiring-lake-wobegon-...
[edit] -- btw, using the new-shiny stuff is not all-or-none. You can still use tried and true tech along the way.
I just don't think research done from the perspective of the biggest tech company in the world has any relevance on 99.9% of small tech startups.
Your main focus should always be to ship good user tested product, and I agree you don't have to be the best programmer to build something that users want and like.
The downside is it could backfire on who you're able to hire. It could just lure people who will either want to migrate to the next new-and-shiny or just leave quickly.