So, is the general vibe here that the James Webb isn't a real telescope, or that it might just be a piece of space junk utterly incapable of doing what NASA claims?
Yes, that's my opinion. From my perspective, the claim that they can broadcast HIGH DEFINITION image data from a million miles away is preposterous. To get that kind of bandwidth, you'd need a relatively narrow band, and the narrower the band, the worse the range ... AND you've have to hit the target on a receiver spot on, while the earth is "rotating" at 1000MPH and Webb is travelling at high speed. Just not possible.
If it were possible, this would long ago have been exploited by the commercial sector. You'd have radio towers beaming high-speed internet all over the world. I'd get on my ham radio and send high definition data halfway around the world with some kind of modem.
Yes, you have cell towers that are capable of higher bandwidth ... but, as I mentioned, their RANGE decreases significantly. You have to be within a mile or two of a cell tower to get that kind of bandwith. And, with 5G, where you have even higher bandwidth, you have to be even much closer than that to a cell tower. And to get that kind of bandwidth, these towers require a huge amount of electricity.
Ah, you could say, but they get better range because they don't have atmosphere in space. On the contrary, the massive amount of radiation in space, or, rather, alleged to be in alleged space, especially as the signals made it back through the Van Allen Belt, the amount of radiation would create massive interference and hopelessly corrupt the data. You also have the magic "Ionosphere" which bounces radio waves off it it when it's convenient (to explain how radio waves came travel halfway around a "globe") but then completely disappers when its' incoveniet, alllowing radio signals to pass through without issues.
This is simply not possible that a satellite is beaming high definition pictures back to earth from a million miles away. That technology does not exist, or else we'd see it being exploited for commercial purposes. And, no, NASA doesn't have some secret/magic stuff. With regard to most technology, they're literally 10-20 years behind. I worked there doing software development for about 4-5 years. Project cycles were so long and so "waterfall" in nature that you had to select the technology at the beginning of the project. By the time the project is ready to go, 10 years have passed, and the technology that had been selected was hopelessly obsolete and out of date. We had lots of firedrills where NASA had to frantically buy up the entire inventory of a manufacturer or buy the source code from a software company that was on the verge of going out to business ... since they could not get that obsolete tech anymore. So, no, NASA does not have some magic tech that's 20 years ahead of the commercial sector. It's generally the opposite.