I believe there is a growing number of startups that are realizing the importance of launching with a (fairly) polished product. There's just a ton of startups now, and standing out in the crowd is becoming more difficult.
When I hear "launch early" what I personally take it to mean is "iterate based on _real_ customer feedback", with the intention being you'll minimize wasted work. But this is how you should be running your business all the time - not just at the MVP stage.
Agreed entirely about iterating based on real customer feedback, though.
Then I saw your comment about iterating on real customer feedback and I realised there's no difference between "releasing early" and "release a beta [early and get feedback early]", and obviously the time to release a beta varies depending on the product. If you think about Google or Shazaam or any technology-based service, the core algorithms took time to develop to a point where a beta made sense because access to the technology was the product. Or am I missing something?)
It takes a lot of courage to burst your own bubble at the earliest possible opportunity.
If you want to try stuff out early, also consider in-person guerrilla user testing, running ad-driven tests on a fake brand, buying low-cost traffic, and asking fellow entrepreneurs to try things out. For more on this, the Lean Startup Circle mailing list has a lot of good ideas.