It's a good point that synergy is a major issue here. This also ties into Civ6's general design philosophy which seems to be "more is more" (and more with more on top is even more), which really shows with how they designed NFP (and is perhaps THE major flaw of Civ6). I'm not sure I agree that Monumentality is not in itself inherently broken, but that is probably a moot point, because as you say, the game is played as a whole, not as each individual part in isolation. The fact that Monumentality repeats over three eras - and can be picked repeatedly over all three eras - is obviously another major issue here, which ties into the design of the era system, which merits a topic of its own.
There are some interesting points brought up wrt. pantheons and whether the desert/tundra/jungle-pantheons should be nerfed. I'd probably go the other way: I'd leave these pantheons as they are, but boost some of (a lot of) the other pantheons and increase the faith cost for buying things to make faith less valuable as a universal currency. The reason I would do this is that a lot of pantheons have already been nerfed into uselessness - Harvest was completely removed, and both Earth Goddess and Divine Spark have been nerfed to the point where they don't make much of a difference. I often find myself in the situation where I need to pick a pantheon and look at a list with 20-or-something choices and literally think: All of these are trash for me in my current situation. When the choice is between getting perhaps +2-3 culture from plantations or pastures, or getting perhaps 3-4 faith from quarries or mines, it feels rather boring.
I certainly agree with the last part. Just out of curiosity, where are the governor promos better used? This is an honest question from my end, because I find the governors to be mostly trash. Obviously you want to throw at least three promos into Pingala for start, to get the double GP promo, in most situations I also want both the culture and science boost. Throwing at least one promo into recruiting Armani also seems universally usefull, and sometimes if a really important city state comes up and is contested (Bologna, Yerevan, Valletta?), going for the level 3 promotion on Armani can also be a priority (but I'd argue that often this can wait). Depending on food and chopping availability, recruiting Magnus and giving him the settler promotion is also generally useful (but if you have a city with good food access, for instance sugar or spice resources, I'd argue the settler promotion is actually less useful than it looks on paper, because the city will most likely be housing capped and will replace the lost population in a couple of turn anyway). On the other hand, I practically never see any reason to recruit Victor, Liang or Reyna until later.
So depending on your priorities, you can realistically have Moksha up and running by the time you finish Guilds and Medieval Fairs in late Medieval era (by this time, you will have 6 promotions from civics and 3 from Government Plaza). Getting one or two governor promotions from huts will obviously help a lot in giving you the liberty to invest heavily in Moksha, but unlocking Moksha by late medieval is just about perfect timing to having your faith economy set up and having had the opportunity to benefit from Monumentality in classical and/or medieval era.