Uncoated lens are prone to scratches. Coated lenses added a hard layer that protected the glass.

I think that's why uncoated lenses get the reputation for being "soft." Optical glass can't really be soft. Otherwise, it would bend and melt if left in a hot car.

The thing with uncoated lenses is how they were handled over the years. Aggressive cleaning has caused many to have "surface cleaning" marks, which are just minute scratches. I've had several lenses that have been damaged by this.

There also is a natural process called "blooming," which affects some uncoated lenses. The result is that it can help to reduce intralens reflections, although it doesn't protect the lens like anti-reflective coating does.