Well drawing with a mouse goes okay too.. so far I can't really tell the difference between things I've drawn with the tablet and what I've drawn with the mouse. It does make it a lot easier though.. only had it a day and I'm using the pen for everything.
Ofcourse they can call theirself artists. Not everyone can afford a tablet. I know people who use their mouse, and produce awesome work ! I prefer my tablet though
Tablets are awesome for editing/touching up lots of photos in one go. I get really bad 'mouse cramp' if I'm not using the tablet.
Xabber is right. I haven't been able to afford a tablet for a long time (plus it's gotta work with Linux, tho Wacom's pretty good with that). As far as I'm concerned, if you can make the same graphics with a mouse as those toting tablets, not only are you an "artist", but a better one even, seeing's how tablets do a lot of work for you. A tablet would likely give me a lot more control with Flash, which is the only graphics programme I've ever considered spending the money on a tablet for. In Flash, it's like my mouse is being used by my non-writing hand. Never says someone's not an artist because they don't have some tool. The results of the art name the artist, not the tools.