You're missing the point completely. We (at least, I think most of us) are not being beaten by coalitions. We're tired of beating said coalition and getting almost nothing in return. So, you beat a coalition get 3 provinces. Couple years later, you beat another coalition, get 3 more. Beat the same coalition again, 3 more.exactly. so when your only strategy is annex neighbour's get beaten by coalition don't come to the forums and complain.
It's boring and not even close to rewarding. You want suggestions?
1- Make your country size, the annexed country size, your army size, manpower and army power factors in a coalition. The stronger you are, the stronger the coalition gets.
2- Fix coalition warscore. I don't want to beat a coalition down to 99% score just to get 3 provinces.
3- More rebels on OE. 300%+ should be really hard to handle, now it's quite easy.