I used to believe all-season tires were useless in winter, and probably most brands are, but some aren't bad. I still don't like them, and don't believe even the best all seasons are a match for decent snow tires in snow, but the good ones do work in snow. That all seasons don't work well at all with moderate tread wear is also true.

As far as using snow tires on dry or wet pavement, it depends on the tire. I run Goodyear Ultra Grips, which are H rated and work great in wet weather and just fine dry. They do wear faster than the "million mile" summer tires that some people like, but they also stick far better in the corners than those things do, too. In a hot climate I'm sure snow tires in summer would be a poor choice, but where it barely gets above 80f in the summer, no problem. The biggest differences compared to all seasons in summer is that they're noisy, but I don't mind that, and also that these particular tires, on my car, are very resistant to hydroplaning.

Driving experience is certainly a big part of snow driving, but even a great driver can't make a car go up a steep snowy grade with bad tires.

As they say - YMMV.