...So, which excuse do we make for such missile strikes never being in evidence?
- There exists a defense?
- Bushido rules?
- Nobody wants to destroy a planet if one can conquer it?
- Strikes take place but we don't discuss it with outsiders?
Nothing so mysterious. This may be a bit esoteric, but in fiction -- especially science fiction -- there's much to be said for the "unseen front" where a lot of odd shit happens that you've never seen before. In anime, for example, we have the OVA sidestories in the Gundam universe that tell us that throughout the entire run of Mobile Suit Gundam that was a whole bunch of really interesting shit happening right down the street that nobody even HINTED at. Comic followups and videogames only expand the situation, so instead of the canon being "There is only one Gundam, and Amuro is its pilot," it's now "There are, like, twenty
Gundams, and their pilots are a combination of dorks, mutants and psychopaths... and also, Amuro."
Star Trek isn't so brazen about it, but it's kind of telling that outside the pilot episode, Deep Space Nine contains no overt references to Voyager, and Voyager in turn never mentions Deep Space Nine or even makes any specific references to the events of the Dominion War. Oddly, neither do any of the Trek movies (they mention DS9 only in reference to Worf's background, which coincidentally is exactly as often as DS9 mentions the Enterprise).
Overall, I actually think this is one of those "interesting shit that happened around the corner" situations. I'm sure it and things like it would have happened many times during the war, but nobody named Sisko was involved, so it was never worthy of mention.