Yeah that is true and plentyoffish.com uses ASP.NET too. I'm just thinking like Amazon/Google/Facebook big and whether that would become an issue.
Yeah, why solve problems that you actually have when you can fantasize about solving problems you don't have instead?
However, the whole topic of this thread is fantasising about the perfect stack for that massive site. Besides which, 30 seconds now could save one year in the future (just think if Netscape had thought ahead).