Earlier quoted context omitted.
Maybe he was an amazing engineer 100s of times better than anyone else on the project...or maybe he was a bottleneck for everyone else. The latter I've seen. A lot. The former I have not.
Not having seen it does not mean it does not exist. I have seen it more than twice. I hope to see it more times. I have also seen -10x engineers. Generally the best you can do is stay well clear.
I am also implying the likelihood of it being that, rather than from a particular perspective an organizational detriment looks like a personal positive (somewhat akin to the 'heroic' team constantly responding to pages in production for their services; not like that lazy team that only works 8 hours a day and never gets paged), seems low. As mentioned, when one person seems to be doing all the work, yeah, it might be they're just amazing, or it might be that the project is badly managed, and so the work can't actually be distributed well. Both can also be true.
I too have seen -10x engineers. Interestingly, others in the company also saw them as +10x. Someone who was the silo for a notoriously difficult part of the system was viewed by management as amazing (after all, he just went and got things done! They could focus their attention elsewhere!). When I then had to dig in, with actual production requirements, I found nothing really worked, nothing was designed well, nothing was documented, and the person was impossible to work with.