I don't buy it. His explanation is more plausible.
We're on-site only in Chicago, NYC, and SFBA, and have to confirm with every candidate that they're willing to work in one of those locations. "Open to relocation" is a sequence of words that gets you past that step in our hiring process. Lots of people can't honestly promise relocation without knowing what the offer is going to be.
No, I think it's a lot more likely that he's simply right, and startups suck at returning email. I base that on grim personal experience as well.
It can be hard to keep up. Lots of people you don't want to say "no" to, and instead ask a bunch of follow up questions or offer some advice to. I end up with an email folder full of those, and a couple weeks later manage to plow through them. Of course, the experience for the candidate is (sadly): mailed, they went dark.
And we care a lot about recruiting; it is probably the thing we care most about (it's the only rational reason I'm on HN, for instance). Lord knows how bad startups that haven't realized how important recruiting is are with emails. Lots of startups still see recruiting as a hazing opportunity.
I took a job at Scribd at least in part because their lead recruiter, Jack, was the only one of six recruiters / companies to whom I spoke who could be bothered to read my individualized cover letter before speaking to me on the phone. I put in 2-3 hours of research per company before applying, and my cover letters were written for the firm and position. Most people couldn't be arsed to read 3-5 paragraphs.
How do you think things would have gone differently if he had answered with a clear yes? I think, at best, he would have gotten a few more phone calls, but the rest of the story would have been the same.
Few startups are well equipped and capable of relocating a mid career developer /w a house and family, and yet they're the ones complaining loudest about not being able to hire enough.
Have YC startups done well with a founder(s) remote after the initial 3 months? For example, two stay there and one moves elsewhere but is able to continue contributing at a founder-level?
I also thought that the results were this poor maybe not because the companies were so bad at communicating with potential hires but because OPs' resumes weren't as interesting as he made them out to be.
I can imagine that things like "Telecommuter?: Pretty please" and - as you mentioned - "Ability to relocate: Open to idea, can't right away" might've turned off a couple of the companies OP contacted.
What I would've liked to have seen was a more generally formulated and well-engineered resume that would've appealed to all but the most incompetent of HR decision makers, or even better, to A/B split test the email copy.
As such I don't think the post was as meaningful as made out to be.
That's why few were interested.