Well, after suggesting trying out the India+Hanging Gardens combo, I thought I'd give it a chance.
So, I booted up a Shuffle Board as my boy Ghandi, and started a Marathon Run. After (sorta) beelining to Irrigation, I went ahead and started the Hanging Gardens in Delhi. I has another city out, though it was only on the ocean. Fast forward give or take 50 turns, and the Hanging Gardens are complete. Using a modded policy (+4 Production in Capital, -4 Gold) made a difference in getting it built. But once it was built, my cities did grow noticably faster. After I built HG, I got another settler out, and before I knew it, that city was also at 5 population.
So, Hanging Gardens needs a civ that synergizes well with it to be more worth it. And the slower the game, the more noticeable the growth. And Marathon is sloooooooow lol.