To watermark or not to watermark?

I have photographer friends and I have graphic design friends, and I consider myself as both. That is why I find it very interesting when I visit blogs I notice a difference between the two.

Photographers always put their watermark on their photos, but graphic designers do not do the same.

Is it that people think photos are more likely to get stolen than steal a logo or just photographers and designers have a different thought on work on the internet.

When I was in middle school, I  had a geocities webpage. I scanned in my photos and I put little designs I made on the internet. I always put a giant watermark on them (thinking back who would want to take art from a middle schooler). In recent years I stopped doing it. I guess I learned that anything I put on the internet is up for grabs, that is the evil of it. If somebody really wanted to steal that photo, no watermark was going to stop them. With advances in Photoshop simple things like watermarks can be taken away. I suppose I hope that people would not steal, or at least ask for permission to use it. I just hate how those pesky watermarks take away from the design or photograph.

It is a fine line from protecting your work, but showcasing it to the world