That is the largest load of crap I've ever heard. Linux is used on a lot of servers because it is stable, it is fast, and it is secure. The thing running against linux is since there are no (good) games written for it and AMD and nVidia feel that improving their 3d drives for linux is a waste of time. If more people use it, the more resources they will dedicate to improving drivers.
FreeBSD was designed for servers, but Apple used it to create Mac OS X.
At work we had a linux server with an uptime of 560 days between restarts. That is the power of linux, show me a Windows machine that will run well after being on that long. I had to restart our Windows servers once a week before we reformatted them with Ubuntu Server instead (we got rid of our only ASP app.)