The funny thing is that we never actually see a Galaxy class destroy any Dominion ship on screen, although it is implied.
In all the battle scenes it's always hard to make out.
In SOA, after the Defiant loses its two escorts, there is a commercial break.
On returning, the Defiant weaving through ships and you can see a Galaxy class ship take out something that looks like a Dominion Battle cruiser.
That scene with the Odyssey did its job-it did make Starfleet and Galaxies look weaker, but, even after taking the pounding it did, it was still strong enough to leave on its own power.
Have to take that into account.