"Of course" the kind of investing Buffett and Munger do/did is the point here, not investing in general. Y Combinator is 1) early stage 2) tech. Neither of which are what Buffett and Munger cared about. You could make a good case that Buffett and Munger are the most "anti-tech" index around, almost a perfect YC hedge.

If it's the most anti-tech then it's relevant as well :)

No one's saying it's not relevant — what's surprising is not the recognition, it's the endorsement.