Freetards == (usually) Linux users who never use software that must be paid for, regardless of how much more useful or efficient it may be compared to the free alternative
"free" in "free software" does not refer to price, but freedom. And some people think that having some short-term "efficency" is not worth the long-term lock-in that results from that "efficiency". The world is full of stories how some company went bankrupt, leaving their users in the cold. The world is full of stories of products that were simply discontinued, while users were simply told to upgrade to some other version. The world is full of stories of how company starts to extract every available penny from their customers, because the customer can't change their software, since they are too deeply invested in that particular software.
There are a lot of people who think that avoiding those situations is worth a lot more than any possible short-term "efficiency-boost" proprietary software might give them. They see proprietary software as handcuffs. At best, they might be golden handcuffs, but they would still be handcuffs. Now, you might disagree with that, but it doesn't really make their view on the matter wrong.
Now, I'm a Mac-user. But before I went to Mac, I used Linux, and I have started to get this feeling that I should go back to Linux. No, I probably would not leave Mac entirely, I would just move from one main OS to two main OS'es.
And the thing is that I see no need for animosity between Mac-users and Linux-users. Macs have benefitted TRENDEMOUSLY from free software, and I have a feeling that it's a lot easier for Linux to interoperate with Macs than it would be to interoperate with Windows. In many ways, there are more similarities between Linux-users and Mac-users. For starters: both groups are passionate about their platform of choice. Have you ever met someone who is a "passionate Windows-user"? I sure as hell haven't.