Earlier quoted context omitted.
All the BSDs emerged from the BSD (Berkeley Standard Distribution) Unix tradition. All offer a generally monolithic "cathedral" style development approach to the OS as a whole (kernel, libraries, utilities, applications), rather than the more piecemeal "bazaar" style favored by most GNU/Linux distros. The BSDs in general have fragmented rather less than GNU/Linux development has, though the latter have also captured…
Note that Android uses a Linux kernel, but a fair amount of BSD in the libs and userland.
Traditional GNU/Linux systems include a great deal of BSD/MIT licensed software. Locally, I've got over 3100 packages installed on a Debian box. Running grep over /usr/share/doc/*/copyright I find:
2555 of these are GPL licensed, 774 BSD, 1462 reference MIT (this may include non-license references, "MIT License" nets 28 entries), 139 Apache, 25 Python, etc.
Stallman's argument is over the core of the OS, which he makes a fair case for being kernel + compiler + core libraries. In the case of Linux, that's straight up GNU for #'s 2 and 3.