system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] Why didn’t Strange use portals to decapitate Thanos?

During End Game, he chose to tie Thanos with magic ropes.
gpt
Thanos is probably too durable to be cut in that way, he was able to use the powerstone on captain Marvel without too much damages to himself and he survived using the IG. 

Strange portals are probably waaaaaayy weaker than the powerstone.