I disagree that skill can't "fix" luck.
Perhaps in the more powergamey versions the "skill" is in building your character and executing sequences such that luck plays no roll: if you set everything up right, you ARE going to WTFPWN your target.
In 5e that's less likely to work. There's probably going to be a greater chance for something to go wrong because of a bad roll on your part, or a good roll from your target.
So where the skill comes in is in being ready for that; in preparing and planning so that a string of bad luck doesn't sink you.
I can't help but think of Jim Collins' most recent book, "Great By Choice". He analyzes a number of very successful companies (which is what he does in all of his books), comparing each one to a competitor that at one point looked similar, but over the long term didn't perform as well. His main finding was that the wildly successful companies prepared for luck, both good and bad, and were better able to capitalize on the former and mitigate the latter. And for both scenarios the key components were resource reserves and disciplined adherence to a plan.
Seems to me there's a lesson for powergamers here. Make sure you conserve resources (spell slots, special abilities) in case things go badly (or have an unexpected opportunity). Have an escape plan. And don't panic and change your plan if the dice surprise you.
It's a different flavor of skill, perhaps, than in previous editions. But I'd argue it's actually a more subtle and harder skill than reading the forums and picking the right build.
All players should be doing this (conserving resources always), not just powergamers