The Ultimate Riding Jacket?

a cycling jacket needs to be one thing above else.... waterproof.

if you get wet, you get very cold very quickly.

if a jacket has zero thermal qualities but is 100% waterproof, you will stay warm, even at the peak of winter, although this implies you keep riding.

That's a sweeping generalisation, and arguably a false one.

A cycling jacket needs to be breathable first and foremost, otherwise you get wet from the inside from your own sweat. I've ridden in a softshell jacket, a Gore one to be precise, in the pouring rain in February but have stayed warm due to the thermal qualities of the jacket.