"The thrust of your argument though is to imply that summer tyres
made of a compound closer to that of winter tyres, even if without the
tread. But summer tyres already are made of what the manufacturers
as an 'optimised' compound balancing 'softness' with wear. "
Even among summer tires there can be considerable variation in the
characteristics of the particular tires. It's not like there is one
formulation for summer, one for winter and that's all there is to it.
Look at charts of tire performance, and you will see that some summer
tires are optimized for traction, which means they use a stickier
formulation. Consequently, they don't last for as many miles. Other
summer tires have less desirable traction characteristics, but will
last much longer because they are made of a more durable, but less
Winter tires are generally optomized for better traction, which means
stickier. I'm not sure how much that would really help in snow, where
the tread pattern is probably most important. But on wet or slick
pavement, which also occurs in winter, the stickier tire will do better