Transcription
Have you ever wondered why Doctor Strange didn't trap Thanos in a time loop? Just like he did with Dormamu.
See, with Dormamu, Strange used the time stone to lock them both in an endless loop. Every time Dormamu killed him, the loop restarted from the same point. But here's the twist. Strange is a human bound by time. Dormamu isn't. He exists in the dark dimension, a place beyond time itself.
"What is happening?"
"This is time. endless looped time."
So, while Strange experienced every death but forgot them instantly, Dormamu didn't. For him, it was happening again and again forever. That's why he finally gave up and made a deal with Strange.
Now, Thanos is different. He lives within time. He's not outside of it like Dormamu. If Strange tried the same trick, both of them would just keep looping endlessly, never realizing it. No progress, no victory, just infinite repetition.
So, yeah, Strange couldn't just pull another Dormamu. I've come to bargain moment.