Just for fun: what exactly could the parent have said to change your mind? Because if the answer is "nothing", then you're a rock.
It’s actually super straightforward.
The response seems “opposite” what was said because if you read between the lines, the whole comment was about hypothetical future improvements to the cost dynamics.
It's perfectly fair to say that constructing a road to a remote community will mean better ... everything ... for that community, but you're blaming them for not also building a hospital and a school at the same time as the road.
I mean, yeah, technically it's possible that we lose current capacity and we never get enough space capacity to make up for it but if you argue for this particular outcome, I think it's rather improbable. The parent made a very good point: cheaper and better lift to orbit means better ... everything. It would mean you have cost and capacity improvements for the whole chain, and yet nobody bothers to use this for JWST successors. That's a very thin line of probability you'd be arguing for.
And no, the condition doesn’t need to be that nobody bothers to use it, it’s that it doesn’t get used at such a scale on a timeframe people care about to replace the infrastructure it destroyed.
Everything holds back more space-based telescopes - launch capacity, manufacturing capacity, research ideas. But the cheaper launching becomes, the more funding can be devoted to other parts (although something like Amdahl's law will apply), and may even trigger a virtuous cycle where cheaper launches mean you can get away with more standardised, less hardened hardware, which in is then lighter and can be launched more easily, and...
> are those telescopes going to have the same availability to researchers as terrestrial ones?
No, of course not, space telescopes are massively oversubscribed and difficult for even superstar researchers to get time on. That's exactly why we want to launch more of them.