“Some people say 100% cotton thread breaks easier than blend or polyester. So far I haven’t had any bad experience with cotton threats though.”

Cotton thread is just objectively weaker than polyester thread, but I’ve never had that be an issue while sewing.

And in terms of the thread tearing when it’s sewn into a seam, sometimes that’s a feature, not a bug: sometimes it’s better to have the seam blow out and need to be resewn than for expensive or delicate fabric to tear. The right thread for the situation is always relative