2. There is more competition. For the most part, all games are competing for the same audience within genres, and there is a lot of cross-genre intersection of audiences (e.g. people that are into both JRPGs and fighting games). On the other hand, there doesn't necessarily need to be as much cross-over between the intended audience of web sites.
3. There are fewer complementary products (related to #2). GMail doesn't compete with eBay, but Mario competes with Sonic.
4. 'The Evil Empire' A good portion of game development now happens under the Electronic Arts umbrella (at least as I understand it). Their corporate culture seems to scream 'big company' with all of the stories of them living off of the life that they suck out of new hires working 80+ hour weeks.