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.