A study of ambulances in Quebec determined that their best option was to run winter tires year round. The study noted that performance wise there was no downside to the winters in the summer, and the only downside to running the winter tires year round was slightly faster tire wear, however the slightly faster wear was cheaper than the labour to swap twice a year and the storage for the extra sets of tires.
Now for a normal person the economics are slightly different as storing wheels is usually free in your garage at home, and if you do your own changes, those are dirt cheap as well. The extra tire wear then becomes relevant. You also get slightly better fuel economy on summer tires, and a slightly quieter/smoother ride.
But if you are ok with a bit more wear (and it's really not that huge an amount) then there is no need to switch to summer tires, the winters perform just fine.
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Do you have a citation for that? because a frequent condition that winter tires have to deal with is a thin layer of water on top of ice, so generally I would expect them to do well in this situation (and the study I referred to earlier did not note that as a downside)