Hm....
What a slow and calm theory.
This in my opinion really hurts alot of characters who rely on a kill move to make ends meet.
Sure its a fine concept for characters who's killing while racking up damage is a second nature, but for the characters who have issues landing a decent kill--or to better rephrase, characters who rely on a set kill move to stay in the game (i.e. Sonic, Falco, Fox, Sheik, etc) this hurts them and their style.
Yeah the "elite" players don't have to worry about it, because they play the top/high tier characters, basically for their kill strength, pretty contradictory to your theory.
Seriously, think about it for a second.
Why would the pros use characters like Meta Knight, Snake, Marth, etc if they didn't have the killing power/ability needed to get the job done?
This isn't the kind of fighting game with health bars, where your said theory is irrefutably correct, this is a game where a kill move is needed to get the advantage.
It is true that range, priority, power, and speed are all things that are needed to be factored in equally, but in the end it all comes down to who kills whom first, and the better character + better player is bound to get that done. It's what determines what characters are better than others, and more importantly what players are better than others.
And thats not even counting in stale move negation.
If the primary purpose was just to rack up damage, then (using Fox as an example) his up smash should be used commonly, even at lower percentages when it won't kill. The up smash is Fox's primary kill move, if it becomes stale, the opponent will survive at higher percentages, thus giving Fox more time to take damage. Sure you can unstale the move with a down air and a few lasers, but why factor that in if you're primary goal is to just build up damage until stale move negation no longer matters when a simple dash attack is enough to kill?
The goal of the game is to kill, and all the better if all the faster.
Because it's not as cut and dried as it was in melee, doesn't mean it should be scrapped. You just need to approach it differently, this isn't Melee after all.