I just discovered, that the city will no longer be a capital after that. So, this way the opponent's capital is not at its original spot, and you are not a warmonger 
My question is, is this enough of a blow for the opposing civ to justify this as a possible strategy for 'peaceful' games? The original capital seems to be somewhat less important in Civ VI than in V, even though it'll still probably be the best city spot around...

My question is, is this enough of a blow for the opposing civ to justify this as a possible strategy for 'peaceful' games? The original capital seems to be somewhat less important in Civ VI than in V, even though it'll still probably be the best city spot around...