should dean just have said yes to michael in season 5?

I think in retrospect, dean shouldnt have done it to a certain extent, cause idk, we dont know if michael from earth 1 had the exact same personality as michael from earth 2 who did eventually take over deans body and tried to end the world cause there was no dean in earth 2.

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that being said, i do at the same time think dean should have said yes, they obviously kept it off for as long as possible for plot reasons but i didnt like the reasoning, from what i gathered the battle between michael and lucifer would have taken out people i guess, half the planet, idk but that was false, cause even when michael and lucifer became ultra powerful in season 14 and battled, no damage was done in the ripple effect, they fought in a church and even the church stood still after that, so i dont get it, it felt like a plot hole. They could have at least said dean was scared michael wouldnt be true to his word and end up betraying him after he kills lucifer which he did do in earth 2 but we dont know if earth 1 would have done the same thing. If dean had kept michael in him, they'd probably avoid a ton of problems too and maybe there wouldnt be a need for 10 more seasons. What do you all think?