"They" are the advocates, the zealots, the people that insist on flogging what is a basically serviceable server OS with a tacked-on graphical environment and a bunch of software with shoddy UI design as the Cure for All Ills in modern computing and the One True Windows-Slayer.
Seriously commodorejohn, in which century are you living ?
I use Linux as my main OS but don't feel the need to argue to other people they should switch to Linux; like all other Linux users I know. This time has long passed.
In this day and age the best place to find a zealot is in the world where everything starts with a 'i'.
