They do, no joke, and they have for many years.
Back in the late 90s, Macs had over a 1000 viruses, linux, less than 10. (It's been a few years, I forget the exact numbers.)
Did those infections occur a lot? No, but it did happen sometimes.
After all, there's a huge benefit to NOT being the most common user OS. Those scum writing the malware usually want to hit as many victims as possible, and if there's an OS that has 70% or more of the desktops out there, it's pretty obvious what they will aim for.
If you want to continue to believe marketing and fanboys, that's up to you, but don't be surprised when you get infected by some kind of malware for not taking the proper precautions because you believe in computing myths and the protective power of obscurity is magically unbeatable.
By the way, I've done the tech support, and have seen the reality, this isn't just some random opinion. If you don't believe me, that's your problem.