The sample size isn't even close to big enough to draw meaningful conclusions. The number of VC backed startups that succeed is tiny even in the general population. It helps that there are now examples like Gitlab, but ultimately the default option is still hiring local with butts-in-seats. As with most things, there are many followers and very few leaders.
However, I think economics will increasingly drive the adoption. The price of both devs and real estate is overwhelming in the major US startup hubs.
And while finding great talent is always hard, the difficulty still varies drastically by region. Eight years ago Seattle was a sweet spot with an abundance of great talent priced significantly below the bay area. Seattle's upside has since diminished as everyone and their grandmother set up engineering centers in the area, creating strong competition for talent. Two years ago, I found hiring a solid team in Tel Aviv to be significantly easier than Seattle of the same time period.
One of the nasty barriers to going remote-only is legal. Even if you limit scope to the US, each state you hire in potentially establishes a legal nexus, exposing you to yet another set of tax and employment laws. One way companies attempt to work around this is through contractor relationships, but at both the IRS and state level that doesn't always hold up to scrutiny.
If you go overseas, you also get the accounting headaches of apportioning cost-transfers to the subsidiaries and HR headaches of getting benefits and payroll setup.
But the legal, accounting, HR, and even key-hire pipelines are all things YC can help with given their scale and personal networks.