As requested by a moderator, this question as been separated from my question about microkernel-based operating systems.
In the 1980's, the team that developed C and Unix developed a distributed operating system Plan 9 from Bell Labs. Its descendant Inferno is still with us. Given its impeccable pedigree, the fact that Unix's own creators agree it is better, and the fact that the are accustomed to ideas such as that of a virtual machine today, one would have expected such operating systems to have replaced Linux, Windows, and so on. But this hasn't happened.
Wikipedia cites several opinions as to the probably reasons for the failure of Plan 9, including Eric Raymond's:
It looks like Plan 9 failed simply because it fell short of being a compelling enough improvement on Unix to displace its ancestor. Compared to Plan 9, Unix creaks and clanks and has obvious rust spots, but it gets the job done well enough to hold its position. There is a lesson here for ambitious system architects: the most dangerous enemy of a better solution is an existing codebase that is just good enough.
However, to choose one pet example, in another domain, platforms such as lichess prove that a new upstart platform (in lichess's case a chess platform) can displace established platforms if it offers a compelling enough advantage in terms of a user-friendly experience.
So I would like to ask, why has the world not switched over to Inferno? What, in fact, prevents the world from migrating to distributed OS's, particularly given that virtual machines, multiple CPUs, etc. are commonplace? Is there a "hard barrier" that Inferno has not crossed in terms of its capabilities?