EDIT: With regards to the OP, I think the MAYA design principle makes a lot of sense.
Agreed.
5e definitely found the right compromise between advanced and acceptable.
This was one of my major issues with the game, and sadly this problem persists in one of my 5e groups as I have two new players who simply cannot comprehend ToM
TotM may be a relatively new label, but the necessity of playing without a play surface has been around as long as D&D has been played in tiny dorm rooms and the like.
It really is kind of an "advanced technique" though, if the system doesn't have fairly solid support for it (Like 13th Age, for example). It's just not that easy for new/casual players - and just plain always hard for some people (people with as much right to enjoy an RPG as anyone else) because our brains aren't all identically wired, and the wiring that makes you good at one thing might not work so well for another - or DMs to visualize a detailed environment, 4-6 PCs, and however many enemies they're fighting, and all their special relationships to eachother, and track them as they change turn-to-turn.
(Really, when you think about it, it's something of a feat to run TotM well, at all.)
5e, in particular, doesn't so much support or facilitate TotM so much as minimize the advantages of play surface. In other games/ed (like the other WotC eds or 2e w/C&T, or 1e, for that matter) using a surface might let you use detailed movement/facing/positioning-affecting features available the PCs & monsters, AE templates, zones, terrain features and the like to create a dynamic, detailed battle with tactics developing over the course of it. In 5e, it'll play out about like it would vaguely-tracked without any play aids, because those features aren't there to begin with.
being avid fans of Matt Mercer, they have been trained in the way of grid combat exclusively.
I dislike this 'forced' style of play on me so much that I have decided that when this mini-campaign is over (approximately 3 sessions left) I will unlikely DM for them again. I prefer to save BG combat for boss-end/complex encounters, not every other filler combat.
That is a good policy - saving the grid for BBEG fights and complex set-pieces, that is, not excluding players from your game because they have trouble keeping track of your descriptions in a simpler combat you're running TotM.
In a simple fight, the effort of acquiring or drawing a map, and setting up might exceed the extra trouble of repeated descriptions and confusion from running it TotM. In a complex battle, the overhead of putting down a map & minis easily pays for itself.