That is true, but it was designed specifically to perform certain tasks. It’s capable of much more, but those are essentially bonus stretch goals. Nobody is saying a second JWST would have no value, or couldn’t do useful science, that’s a gross mischaracterisation. There are diminishing returns, that’s all.

We all want more science, the question is what’s the best use of 3-4 Bn in extra funds. The real question is which other future telescopes and space missions would you cancel to get a second JWST?

Reminds me of when Seattle finished boring a transit line with their zillion dollar tunnel boring machine, they cut it up and sold it for scrap. Never mind that the machine could have just kept right on boring, extending the line.