I don't think that's right. Movies use all sorts of devices to engage their audience. And a lot of them rely on surprise. If they tell you what they're about to do just before you see it happen "for real" - the effect is obviously compromised.

For me the problem with spoilers is not about knowing what is going to happen. A spoiler primes me to be on the lookout for when the spoiled thing happens, and THAT is what most ruins the experience for me.

Of course a great movie can't fully rely on a plot-twist as it's central supporting structure, but it can be a nice spice that can get entirely muted by a spoiler.