Although I agree that "www" isn't really needed, this is one of those conventions that should have been corrected on day 1 or not at all. To change it now only invites people to encounter more errors than necessary.
There's no way 100% of web sites will change to this. So maybe half the time I'll get an error if I get in the habit of writing web page links to use "xyz.com" instead of "www.xyz.com", or typing them as such in my browser.
Conversely, no business in its right mind would accept only "mybusiness.com", scaring customers away by returning an error for "www.mybusiness.com". Of course they'll accept both, so why not use the one that's sure to work?
I didn't know it was deprecated, but I know people still use it. Especially in casual conversation between non-geeks. I hear it all the time. "Oh, I got the CD to get on to the internet at Double-U Double-U Double-U Dot AOL Dot com"
That last part was a joke, but people still use it.
There's no way 100% of web sites will change to this. So maybe half the time I'll get an error if I get in the habit of writing web page links to use "xyz.com" instead of "www.xyz.com", or typing them as such in my browser.
Conversely, no business in its right mind would accept only "mybusiness.com", scaring customers away by returning an error for "www.mybusiness.com". Of course they'll accept both, so why not use the one that's sure to work?