There are actually many printers that are requiring higher DPIs for printing. I used to work at 300 DPI, but the last company I did pages for wanted 400 DPI for color and 600 DPI for black and white.
That said, even if print doesn't need to be that big, there are benefits to working at a higher DPI. I work at 600 DPI for my comic so I can ink without an anti-aliased brush to make it faster to color it, while still maintaining a good line quality and being able to get in a decent amount of detail in my images.
As long as images are properly resized for web before posting online, there's no harm in working larger. And it's always better to work bigger, because you can always scale down. If you do pages at 300 DPI and find out they need to be 400 for the printer you're working with, you can't scale up without losing quality.