Locks have always been relioant on gear crutches since vanilla? Simply not true, not true at all.
And as I pointed out, at their current design state, demo locks are wildly overpowered with the T18 and class trinket, because they synergise with the redesign in a way they were very obviously never intended to so, and my guess is that Blizzard either didn't spot it, or did and just didn't care about it, because it doesn't matter much for the six weeks or prepatch play.
But unless demonology gets some serious buffs to base damage output which isn;t great even on a Patchwerk where you don't have to move and can align everything properly - then they won't be used, because the mixture of at best mediocre damage combined with an extremely poor toolbox and comparatively having to work your tits off for little reward is deadly.
Destruction is easier, more rewarding, and has better tools for dealing with an encounter than demonology. And plenty of classes are easier, more rewarding and have better tools for any situation than destruction.
Given a fresh start no one in their right minds would chose a warlock of any spec over an MM hunter, unless they thought that class fantasy was more important than anything else. I doubt you'll be seeing many if any locks in Mythic progression.
As it stands demonology doesn;t even have a "gear crutch" for Legion, sinc eobviously, the whole idea is not to keep T18 and class trinkets - which are only wildly overpowered because they were designed for WoD demo, not Legion demo. There just doesn;t seem to be any Legion gear crutch and it would be horrible if there was.
So at the moment demo in live is doing at least 50% more damage than it should and you are dumping some of the rotation - that's not really a gear crutch, it's a broken class with broken gear producing hugely skewed results...and very false impressions.