NASA, ESA and CSA have collaborated on the telescope since 1996. [...] ESA is providing the NIRSpec instrument, the Optical Bench Assembly of the MIRI instrument, an Ariane 5 ECA launcher, and manpower to support operations. The CSA will provide the Fine Guidance Sensor and the Near-Infrared Imager Slitless Spectrograph plus manpower to support operations.
Several thousand scientists, engineers, and technicians spanning 15 countries have contributed to the build, test and integration of the JWST. A total of 258 companies, government agencies, and academic institutions are participating in the pre-launch project; 142 from the United States, 104 from 12 European countries, and 12 from Canada. Other countries as NASA partners, such as Australia, have or will be involved in post-launch operation.
ESA and CSA to name a couple. Probably also lots of other uncredited, small cross-institutional interactions. Not to mention all the details of the launch. I was partly trying to speculate as to why the comment appeared to be getting down-voted. But I guess it's also my opinion that it's kinda weird to claim that no one else could have done it. Who else are we talking about other than earthbound humans?
