I said nothing about bad starts! I simply said good starts can be nullfied. If you have a bad start, you are still screwed but at least you can help screw the better guy, or play smart let them weaken each other then pounce.
I've found in all the multiplayer games i play that NW's do give you a significant advantage, however that advantage does mean you get ganked. You can be left out of trades etc, just to stop you from growing more. I had one game where a friend of mine settled FOY as spain in like 30 turns. Me and the other guy on our continent declared war on him instantly. Constantly pressuring him with units, he couldn't expand and make use of that happiness. He lost the FOY city and it got razed as soon as catapults came in for the both of us.
Clearly multiplayer can be a very different game depending on who you're playing with and clearly me and my friends play quite differently to a lot of people. I'm more than happy with the current NW's though, i think it makes for some great gameplay
Even if you can't knock them out as soon as they get it, you can keep up the pressure or team up and take them down a peg when it is feasible. One player cannot survive on his continent against two or three players teaming against him in the long run. If you get knocked out by a skilldorado player before an effective group attack can be orchestrated you've not been focussing on your army enough though, or your fellow players and yourself are not forming an effective strategy of defence until you can attack. You can always say benefit of hindsight and stuff, but if someone gets a top quality natural wonder or start, you've got to be prepared to go more military focussed early.
I'm not saying it's not difficult, but there are natural balances like that built in. If you focus on taking out the runaway, you can take out the runaway most of the time.