I did. To get rid of the Maquis, you either kill enough of them to drive them away, or keep killing them until they are all dead.
But you didn't see that evidence, because the Cardassians neither killed enough Maquis to make them fold, nor eradicated them. From what we see, they didn't even make a serious effort, as the government was bound by the law and treaty and AFAWK obeyed it to the hilt, and the rabble-rousers lacked the means.
No genocidal campaign is in evidence, and the debate is only over whether one was intended or not. Maquis intent to slaughter Cardassians is debatable: the one time we see Eddington in seeming genocidal action, he's doing it as part of a ploy against Starfleet, and he plays it out as if his nerve gas would only evict the Cardassians instead of killing hordes of them. However, it's quite an elaborate ploy if it's only intended to be one-time bluff; the story does seem to suggest that Eddington eventually wanted to nerve-gas every Cardassian within his reach.
Cardassian (any Cardassian) intent to slaughter UFP colonists wholesale is never mentioned, nor seen in action. Starfleet intent to slaughter either Maquis or Cardassians is only discussed once, as a ploy to capture Eddington, although apparently Starfleet afterwards has no quarrel with Sisko for his unauthorized use of genocide as a threat. Dominion/Dukat intent to slaughter just about everybody is obvious, although Dominion uses this threat in great moderation and Dukat in a lunatic quest for vengeance.
Because that would be violation of the treaty and thus an act of war. They are as yet not ready to start the next one.
The people behind the attacks were independents, disowned by their government. Perhaps falsely so, but nevertheless, the actions of the independents would have been no more or less a violation of the treaty if they involved heavy phasers (like those used in the double ambush that Sisko and Dukat witnessed) than if they were limited to the use of hand disruptors or small explosive devices.
If the official Cardassia really wanted the UFP colonists gone by genocidal purge, it should have sponsored the independents into performing the maximum number of planet-shattering, truly genocidal attacks in the minimum number of time. That would have been well within the means of properly armed civilians, and would have caused much less political wrangling than a slow and tortuous ongoing campaign of harrassment. Nuke 'em quick, and lament afterwards that you could not contain your extremists in time - as nobody could be expected to.
Any outright evidence of Klingon and Romulan conquests is also severely lacking, but anyone knows they carved out their empire by conquest and thus must have conquered and subjugated quite a few species.
Oh, that's far from said. Romulans are portrayed as xenophobic and racist, so they might simply have killed all the natives instead of subjugating them. And Klingon tradition of rule over alien subject species is verbally confirmed when we get to see our only good onscreen example, the subjugation of Organia.
The Cardassian Union is no different.
Where would the fun be in that?
Surely the writers strove to make the CU as unique an adversary as they possibly could, nuanced in many ways. It just wouldn't do to summarily dismiss the idea that they might be such small-time players that Bajor is the only thing they ever managed to grab. That would certainly set them apart from those UFP arch-enemies who actually put up respectable resistance in the respective Fed-alien wars.
Timo Saloniemi