Where I saw it, on it’s first run, at least, Schindler’s List didn’t have an intermission.
The last movie I saw that actually had an intermission was Lawrence of Arabia, during its re-release around 1990.
Was Three Kings really that long? Another reason to put it high on the best movie chart. (i.e. the fact that I didn’t notice its length, not that it was long)
As to why they aren’t used, I don’t know. I’ve heard some stories that in times gone by, it was not uncommon to enter & leave a movie while it was running – maybe because films were seen more as escapism and less as something to pay attention to. The intermission seems a little like that. As attitudes towards the movies have changed, those making them are perhaps more determined to hold your attention the entire time, and don’t want the interruption.