The degree of exponential growth is still in question but the fact that it will be exponential, and will cause a huge headache eventually if left unchecked is pretty much accepted.

However, enforcement would run into the same problem that enforcing any resource in the international commons runs into, such as overfishing, oceanic/atmospheric pollution, etc.

Since it requires coordinated collective action of every space launching nation, it would require something like the UN security council to really punish nations that defect from the agreed upon program. which opens another can of worms.