But if I felt contagious-but-not-really-impaired, just sneezing or whatnot, I don't see any reason personally why sitting (at home) at a computer and watching Netflix is going to help me recover faster than sitting (at home) at a computer and working.
Also, possibly save your coworkers from the infection. I'd rather have my coworkers take a WFH than come in if they feel low.
Cold and flu kill old people. By going into work you are spreading disease to your co-workers, who then spread it to their family, who then risk death because you didn't want to work from home.
But yes, I have great distaste for people who could work from home while sick and instead ruin the productivity of the entire office for what can be months afterward.