Ultimately, both arguments are true.
Developing nations have a claim. It's deeply unfair that wealthy nations who have emitted a lot of carbon get permission to keep emitting more as a result. But also.. if developing nations fully stake this claim by increasing their emissions or even flatlining then the game is lost.
This is the problem with thinking in absolutes. The alternative is making some concessions and moving forward regardless because of belief in the mission. Europe is already in the same per capita ballpark as china. If the US/Australia/etc had gotten themselves near this per capita level, the politics of developed/developing economies would have softened somewhat. The fairness issues aren't as sharp once emissions are similar.
Realistically, we are not politically structured (as a world) to deal with carbon reduction well. Nationalism is the dominant paradigm both structurally/politically and ideologically. It's a weak paradigm for global action.
I emphasize the politics over the economics, though obviously both intertwine. Long term, there are economic upsides as well as downsides to carbon reduction. As a blind (long) bet, I'd always bet on new energy paradigms being a good thing. The long tail upside is especially interesting. Within a functioning polity, that's something you can work. The world isn't.