You can also get issues with chain rub on the middle and large ring while using the granny, if you are trying to use smaller cogs. Recall that some folks just don't like to shift the front. Of course your ability to use small cogs is limited by the rear derailleur capacity, but a lot of folks just don't pay attention to such mundane stuff.

1x seems perfect for folks who find the range of an 11-46 is good for the terrain they ride, don't mind huge gaps between shifts and like the concept of making things simpler by eliminating the front derailleur and shifter. I'd rather have smaller gaps in the cogset and find the cadence I want. I'd also rather have XT Di2, but Santa is not likely to get me that this year (or next). Than I'd get a double crank and let Synchro Shift do it's magic.