Yes, the luck can balance itself out, that's still more luck though.
If the luck balances out, you can't really say island T17s are more luck based.
It's as if people associate luck with being less skilled or bad, that isn't what i'm saying at all.
By definition, the more luck based something is, the less skill involved. They're inversely correlated. I don't think anyone thinks you're saying that T17 doesn't involve any skill at all, but by saying it's one of the more luck based schemes (but contradicting yourself by saying the luck balances out), you're effectively saying that it takes less skill than other schemes.
Basically every non-race scheme has a fair amount of luck in it but they tend to even out over time. I think one potential reason for lower win rates for T17 in past leagues is that it hasn't always been the most popular competitive scheme. If you only have the top T17 players playing each other, there won't be as high % win rate.
It's like Hearthstone or MTG or other card games.. they have heavy luck components and at the top level the highest win rates tend to start to even out at something like 70%. But there are dramatic skill differences in those games, even with the fairly limited number of decisions that can be made at each turn (compared to most worms schemes where the options are pretty limitless).