It was all true 25 years ago.
The sellers want to sell as many tires as possible so they're motivated to define and exploit differences in tires. Some of the info I've read is nonsense, but I'd be crazy to take a chance of misinforming people here in any general way. For example, the sites say all season tires cease being effective in conditions under 45 degrees (f). That's absolute hogwash, they'll go much lower than that before any compromise in pliability.
Industry has a tendency to overstate safety of their products for good reason, and for the most part, I think that's smart of them.
Just have two sets of tires, that's all. It's just money, after all.