Okay, I know here are the internet we all love to be devil's advocates, contrarians, apologists, and generally derive validation of negging someone else's negging. Hey, I feel you! But....Maya does seem to be a civ you only play if you're looking for a handicap to overcome, not a specialty to explore and exploit.
The observatory is a campus replacement that takes all the yummy bonuses for mountains, fissures, rainforests, and coral, and then swaps them out a big bonus for plantations and a meager bonus for farms. That ain't the way uniques are supposed to work in Civ VI. In the final tally, they're actually supposed to be an improvement over what they're replacing. And all the canard arguments about map dependency, but you ultimately have to simply determine one thing: should a Maya player ultimately be expected to come out ahead with the their adjacency bonuses in a way that makes this an appealing alternative to a campus?
Now, if you want a civ that is supposed to be small and compact, it's cool in principle to provide an alternative way to get housing. By cutting off the fresh water bonus (rather than merely reducing it), it kind of liberates the player from the familiar trap of feeling compelled to choose river adjacency over all other considerations. That's all right. But you can't have the compensating factor be farms while the design is also suggesting that empires should be small and compact. You just run of places to put them. It would have helped if city center adjacency to luxuries provided extra housing, instead of extra amenities--which, after all, a small empires doesn't really need.
The worst failing of a small/tall civ in Civ VI is there just isn't anything to do with population, certainly not if you're squashing all the cities and they have to overlap their access. And man, +10% for cities within six tiles, but -15% for those not? Again, there does not seem to be upside there, just handicap to try to break even with.
Unless I've missed some huge benefit--and if I have, I'm all ears--Maya is just a civ for those looking to have a hand tied behind their back, not play devil's advocate for its own sake. And that's fine, but let's try to land on a consensus. I get that some folks want to give Maya a fair shake, but sometimes giving the waiter a thumbs as you fish the the hairs out of your soup and then apply extra elbow grease to cut the shoe-leather steak isn't the fairest thing to do. Sometimes you just gotta send things back and let the kitchen know there's a problem to fix.