Because it's not uniformly developed, there's still 100s of millions who are underdeveloped. If we're sensible we'll cap a limit on what first place should emit per capita and that will be the benchmark everyone targets / settles at. Right now that's high income per capita emissions. Realistically, it doesn't stop until some agreed/enforced per capital emission ceiling and if that agreed ceiling takes us to 4/5/6 degrees then that's where we're going to settle. Ultimately the fair requirement is suggest countries have X historic per captia emissions adjustment to unfuck themselves / prepare for climate change. If wealthy countries are generous they can subsidize the transition, but we know that's unlikely so really it's about how (or whether) to mitigate the free for all.

In an even fairer world, huge renewable exporters would get credit / per capita adjustments for exporting net renewable and fossil exporers would get opposite. Oh and countries with high TFR or advanced economies with high immigration that multiplies an immigrant's emission (i.e. poor -> rich flow) would get penalized. But that's even less likely to happen because it's obvious whose interest these sensible proposals undermine, because climate change isn't a scientific of enviromental problem, it's a geopolitcal one.