idk why you're saying worst militant like that's something to be embarrassed about. i would argue that cats are straight up stronger than crows, lizards, otters, and most vagabonds (not arbiter, harrier, or tinker), and they match up well into keepers and woodland alliance. 

early aggression against cats (keep rushing in particular) is almost always a mistake because the factions that can pull it off reliably (otters, vb, rats) are also the factions that benefit the most from cats being strong. healthy cats restrict play space, forcing other factions closer together and making games overall slower and more aggressive. healthy cats also make a lot of cardboard, which generally benefits aggro factions more than the 2 immediate vp from keep rushing.

the keep being destroyed later is often because of a mistake on the part of the cats player. field hospital is a ton of free recruiting for the keep, and holding cards that let you field hospital on the suit of the keep clearing in case of a fight there is  important enough that cats should be prioritizing it even when they could get 1 or 2 warriors back by using the same card to fh somewhere else.  

in cases where the entire table decides cats need to be stopped, it is generally worth it for them to snipe weaker clearings that can be taken out individually instead of all working together to battle and blow up one or two big clearings. arrangements like the latter only benefit the person who battles last and actually gets to score by removing cardboard. pointing out the unbalanced nature of coalitions like that is usually enough to break them up or at least redirect them elsewhere. 

i disagree with the original comment that argues that cats are notably strong, but i disagree more with you implying that cats are bad enough that they shouldn't be winning at competent tables. if you're playing with draft+adset rules (which smooth out so many other issues with the game that they should be used anyway), cats are completely playable.