We very likely would be better off by redistributing our cap space.
If it's at the cost of Marner, no, we would not. If we want to reallocate cap space, we can do so without getting rid of one of our best players.
I hear defensemen and goalies are useful….
I agree. You should tell Treliving.
If they fail to make it past round 1 again, how does keeping Marner really help?
If they fail to make it past round 1, how does getting rid of one of your best players really help? Change for the sake of change may feel cathartic in post-loss emotion, but gutting your team of one of its best performers doesn't actually accomplish anything positive.
How does repeating the same thing that hasn’t worked that many years help?
We're not repeating the same thing. The team was different in every one of those years, and it will continue being different every year moving forward. And even in some hypothetical world where we could somehow repeat the exact same thing, that wouldn't mean we would get the same outcome anyway. That's not how hockey works.
Besides, in many of those years, it hasn't so much "not worked" as it has not led to the outcome we want for a variety of largely external reasons that aren't improved by losing one of our best players. This is why it's important to learn and understand the reasons that we've actually lost, instead of just looking at the fact that we lost, and then trying to purge anything you've seen before.
Yes, because spending 1/4 of your cap on 2 wingers is a tried and true recipe for playoff success.
There is no "tried and true recipe for playoff success". There are a million different ways to win, and having two elite wingers can certainly be part of one.