Yes. This is very similar. Lots of commenters here seem to be missing that point. Rather than making a low confidence claim about the immediate future (the economy will crash next year) it's making a more confident claim about the distant future (growth rates are unsustainable over the next hundreds or thousands of years without mind-bending physics).
Yes, definitely. This isn't meant to argue that those limits are anywhere nearby.
The significance of the argument is that once everyone accepts that a seemingly-unstoppable exponential growth trend can be halted by far-off limit A, you can start to have productive discussions about whether it can also be halted by more relevant limits B and C. Sometimes the hard part is just getting past the point that an exponential trend ever need stop for any reason.
Or the speed of light when discussing train speeds?
They're real but aren't we miles away? Genuinely curious. Just seems to me that economic organisation hasn't come anywhere near what physics allows.