Well, considering that not razing in domination victories will sink your economy into the trash, it would only be worse. The maintenance can get enormous.
I've done this strategy and it does work. Sort of.
In domination victories, not razing only sends your economy into the toilet because city maintenance > city gold production for your empire.
If you come up with a way to have city maintenance < city gold production, then you're good to go.
Keep in mind, though, each city you found has its own city maintenance, but also raises the city maintenance of all of your other cities until the "number of cities" cost per turn hits 6. (I believe this depends on the map size, but not difficulty or speed, but I could be wrong.)
If you can figure out a way to get at least 6 gold per city (plus distance from capital cost for that city) as soon as a city is founded, then you can found (or capture cities) until the cows come home while still maintaining a healthy economy. As you put buildings in those cities, your economy will only improve. (note: you also have to pay for civic maintenance, but this is only a gold or two more per city, so just get the city to 8-10 gold per turn and you'll be good to go).
Example:
Your empire already contains the Statue of Liberty, Angkor Wat, Apostolic Palace, Spiral Minaret, University of Sankore and throw in Sistine Chapel for good measure. You are running Caste System, Mercantilism and Representation and you founded 2 religions in one city with a holy shrine to each religion in your Wall Street city.
...sound like a pretty unlikely scenario? Sure, if you're just picking wonders at random. Remember that this is a strategy and I think everyone can agree that all of the wonders above plus 2 religions in one city is entirely doable on most difficulty levels.
Now go out and found a city all the way on the other side of the Pangea globe in the middle of a tundra with no roads connecting it. You sent along two missionaries with the Settler, so you can found both religions immediately.
That's 6 gold maintenance (already maxed out), 3-5 gold distance cost and maybe another 1 gold for civics. If you can generate 11 gold per turn, then anything else the city creates is just a bonus to your empire.
The city itself won't generate any trade since you somehow founded the city in the middle of a vast desert without any roads. Add in your 4 trade routes at 1 gold per turn and you get 4 free gold/science/culture depending on your slider. You might as well not work any tiles since it's all desert, so we'll make another merchant. 3 merchants total gives 3 gold and 3 science each. Each of your two religions give 1 gold back in your Wall Street city for a total of 2x(1+.25+.25+.5+1)=6 gold per turn from religions. You also pick up 6 culture and 9-27 great people points per turn from your specialists, but that isn't directly contributing gold, so I won't count it here.
This city is the absolute worst city you could possibly build in the entire planet (except for colony maintenance) and it's costing you 11 gold per turn while generating 15 gold, 9 science and 1 hammer per turn. As soon as you build a temple, you'll pick up another 2 hammers, 2 gold and 2 science from the temple and can work a priest for 2 hammers and 1 gold. It's a little less profit now, but you just went from 1 hammer per turn to 5 hammers per turn by finishing the temple. Build a courthouse after that and you'll see another 5-ish gold per turn profit from reduced maintenance. Connect the city with a road and pick up some commerce. Build a grassland hill and you see the city absolutely take off as you build temples, granaries, courthouses, etc.
...so what's the downside? Wouldn't getting a profit of 9 science, 1 hammer, at least 4-6 gold and 6 culture per turn for even your very worst cities be a great empire? Sure! Who wouldn't like that? The problem is that the time when Infinite City Sprawl would be possible isn't the time that you can do it. In the beginning of the game you won't have Statue of Liberty, 2 religions with Wall Street and any of those other wonders. This strategy only kicks in after many people's games have already been decided. It works. It's fun. It's not at all possible in the early game when there is actually room to go out and sprawl.
When there are tiny islands offshore, I tend to prioritize getting the great lighthouse and fully populating the islands.
