Because the vaccine is not quite 100%. While we are still seeing over 50,000 cases a day, vaccinated people should still wear masks in crowds. It's a numbers game. While this isn't quite how it works, let's say you have a 1 in 20 chance of getting symptomatic COVID-19 compared to an unvaccinated person. Because of community spread, an unvaccinated person has a 1 in 10 chance of catching the disease from, say, eating in a restaurant. That gives the vaccinated person about a 1 in 200 chance. It's a lot, lot, lot lower, but it's not zero.

The CDC just issued new guidelines saying the fully vaccinated no longer need to wear masks outdoors, although if your area still has a mandate, obviously you should.

I get that it feels like a mixed message, but safer isn't safe. And I get that it would feel like more of a reward for getting vaccinated if you could get rid of those dang masks (I hate them too, I have to go somewhere today and it's going to be 90 and grrr). But we just have to be patient a little longer.