I think you're arguing away from what the YC Partners would admit. They didn't fund DropBox because Drew showed up and said, "I don't know if file syncing will work but..." He was a designer who said, "I can make the user experience easier." Whether there were aspects during implementation that were tricky is not surprising but also moot. (And remember Gmail was introduced in 2004; by 2005, AJAX was not as crazy new as you're trying to make it sound.)
YC doesn't fund "hard tech" because they want to make money and the fastest way to make money is to find new uses of existing tech. Now we've found we've driven that car as far as it would go and because we didn't invest in gas (new tech), we're stuck.
I think you're arguing away from what the YC Partners would admit. They didn't fund DropBox because Drew showed up and said, "I don't know if file syncing will work but..." He was a designer who said, "I can make the user experience easier." Whether there were aspects during implementation that were tricky is not surprising but also moot. (And remember Gmail was introduced in 2004; by 2005, AJAX was not as crazy new as you're trying to make it sound.)
YC doesn't fund "hard tech" because they want to make money and the fastest way to make money is to find new uses of existing tech. Now we've found we've driven that car as far as it would go and because we didn't invest in gas (new tech), we're stuck.