Perhaps you simply hear more about Web devs because most Web gigs are relatively small - compared with many of the lower-level jobs. As a result, Web folks are constantly advertising themselves to find the next gig. Also based on this small-job phenomenon, these people may have better skills at marketing themselves.

The other thought that comes to mind is that the results of Web skills are usually apparent in a very short time after the person begins working. The user-interface is the "face" of a long path of other systems that make the whole thing possible. Hence, those persons closest to the UI get associated with the results of all the systems working in tandem. It's as if they themselves made it all happen.