It seems like you're both right. You qualified your statement with "under load". Are a majority of websites/web applications under a significant load? I'd gues

It seems like you're both right. You qualified your statement with "under load". Are a majority of websites/web applications under a significant load? I'd guess the real answer is that, for most websites, they're I/O bound due to the process of sending data between the client and server. However, heavier applications and sites with significant traffic then require more CPU processing, thus becoming CPU bound. I don't have any real expertise, but from everything I've read and seen discussed, this is my interpretation of the issue.