SIMPY, SHADOWS and DEL.ICIO.US all do this wrong I think

I would love to know why services like Simpy and Shadows (to some extent) and del.icio.us all focus on a users tags and not the global perspective. It seems that when I click on a tag on the front page of each of these services that is related to a web page, it lists all the other tagged pages of the same type that the user has posted and not the global point of view. I would have thought that the global frame of reference was more important that a users individual one. For instance I might have one 1 AJAX tag in my profile, what is the point in seeing that, I would be more initerested in what everyone else reckons is AJAX.

The option between a quick search of the users tags and the globally related tags would be nice.

What do you think?