Are you suggesting that every user that has a pre-installed OS, with only
a recovery partition, can't run SFC?
As absurd as it sounds, that is basically the case. Initially sfc may
find required files in the i386 folder (on some OEM installations). If not,
and always once a service pack has been applied, the user can RUN sfc but if
it asks for a Windows media and the user does not have one with the proper
version and service pack level, sfc will not be able to complete. Most
OEMs (Dell being a notable exception) do not even provide a real Windows
media so that a user could (if he had sufficient skill) could make a
slipstreamed update.
Techs, like myself, have to maintain large collections of OS media of
different types and versions and service pack levels to deal with this.