Thats just not true. A lot of good but not great defensive teams have won the chip. Denver being the latest.
Jokic is horrible on perimeter switches and Murray coasts on defense. Porter is pretty meh. Only Gordon and KCP are great, but even they arent DPOY level guys.
DEN is an exception, but even they found a way to play great defense in the playoffs. It could be the case they will never be able to do it again, but in order to win a championship you do have to play great on both ends and they did it. Also, it does not matter if Jokic or Murray is bad in a specific area. If they play good defense, they play good defense and they did.
In any case, I think it's a losing strategy to try to build a contender by ignoring one half of the game. Key and Lauri are not defensive players, for me this conversation needs to start with how we're able to build a strong defense around them.