I don't think others mentioned it, but winters are good anyways even without snow. Below 45F, they're recommended for grip on even dry surfaces over all seasons since the compound is much softer at those temperatures. Something to be more concerned about is because the Model 3 is so low, if side streets get snow plowed into them so that there's a snow ledge, you're likely pushing snow with your bumper. I've pushed fresh light snow for something like 40km before in our AWD, but heavy plowed berms of snow would be a different story.
There's a misconception that the mostly even weight distribution of the Model 3 makes it behave much better. In truth, the weight distribution of most modern vehicles is actually pretty even already (if it does matter that much). My Honda Crosstour 4WD was 56/44. An Escalade is 52/48. Model 3 is 48/52. Something like a Honda Accord might be worse at 62/38, but it's also FWD. And if you think about it, there's plenty of rear-engined RWD sporty cars that would bias the weight on the rear, yet almost no one would claim that makes them good winter vehicles.
The Model 3 AWD versions barely use the front motor at all, so honestly you're not missing much. The rare front motor engagement in slippery situations is delayed and weak, barely helping at all. In truly bad conditions, the Model 3 AWD behaves badly, and like any other RWD car IMO. In better "grippy snow" situations with the correct tires, it's one of the best cars I've driven.
All that said, in something like Seattle for slow moving on uphills and tight streets, the AWD might offer some help on a particularly nasty day since that's just about the only situation where the front motor will engage in Winter.
Model 3, AWD or RWD, is a primarily RWD vehicle. I'd say you need to be comfortable driving a RWD vehicle in the snow to best handle the Model 3. That said, my wife who does not enjoy snow driving at all (and has no experience with RWD) was happy with the Model 3 AWD's behaviour this last Winter when she was driving.