I agree, narrows are better.
In slush perhaps.
In 9 winters and across 4 VAG FWD cars, I have only ever not fitted winter tyres one winter...and I couldn't get out of the driveway in snow.
Since then, I've fitted the same width tyres as standard - except on one occasion where I drove on 205s not 225s - and I can honestly say there was no advantage to the narrower tyres except less squirming & tramlining in slush.
It's the compound and tread pattern that matters.
My Goodyear Eagle F1s (on 2 Golfs currently) are great until the temperature drops below 5 degrees...then they are abysmal. So, at that point the winter tyres go on...and traction, braking grip etc are restored, with the option to drive easily on snow.
Having tried Vredestein Wintrac Xtreme, Michelin Pilot Alpin, Pirelli Snowsport, Avon Ice Touring and Toyo Snowprox, there it little between them for every day use - ANY are streets ahead than summer tyres, no matter how amazing a driver you think you are!
Only the Avons have been narrower and on a smaller wheel (16")...the rest have been standard sized wheels - 18" on the Golfs.
I can see that the storage of wheels & tyres is an issue for many though, and swapping tyres over risks damaging wheels. I guess I'm lucky to have space for spare wheels.
I will never drive through a winter without winter tyres now.