I don't see this as even remotely game breaking. Yes, you've managed to keep growing while producing a settler, but the trade off is a consideradle delay in the production of that settler. Consider the following situation; your early scout units are out doing their thing, you've just produced your worker and want ot start on a settler. Let's say you have a total of 5 hammers+surplus food each turn. With 2 chops you can get a settler out in 10 turns of non-growth (doing things the non-MM way) or you can use the MM described in this thread and have a settle out in 15 turns (3 chops, 13 turns of growth, 2 of non-growth). This assumes each forest takes 5 turns to chop, 1 to move there and 4 for the chop. Note the advantage india has in the early game.
Both ways have their advantages. The non-MM way gets the settler out 5 turns earlier, meaning that your second city is up 5 turns earlier. Using MM, your capital has probably grown a point, and you've been producing units/buildings in the meantime.
It strikes me that which method is 'better' is highly situational. If your early scouts have found an ideal site for your second city, then non-MM is probably better. If good sitres are thin on the ground (lots of jungle/desert or few resources) then getting an extra unit or two out while delaying settler production by using the MM method would be more appropriate. MMing is probably also better for early warmongering.
Edited for clarity