My windows can tilt. Not in the same way, but you can either slide them up or tilt them in. And besides, is being able to tilt your windows really that great?
You'll get ice on the sides, these can't be sufficiently hermetic.
EDIT: With some -30 Celsius outside (EDIT:happened only once or twice in my lifetime, 20 would be something more real) and +15 inside, for example, and usual humidity for a living place, where people cook etc.
What was the temperature inside (don't think anybody remembers or even measures humidity)?
It seems common sense to me that on the sides of a sliding window there'll be very thin gaps, while with a "normal" window there is pressure between parts at all sides.
But I can't say I've seen many sliding windows in my life.
OK, maybe I'm wrong. I'm not very good at physics and easily believe what other people say, but since this thing is really uncommon here - I shouldn't.