[electricmonk]

IANYL.

Just because we haven't seen them doesn't mean there is a market (e.g., b2b) where they may be using them. Also, in this particular instance, since these are registered we can look at what they have provided the USPTO as evidence of use in order to renew the registrations. Microsoft (I think the X involved might actually be the X on the globe logo): https://tsdr.uspto.gov/documentviewer?caseId=sn76041368&docI.... For Microsoft's use before assigning to Meta: https://tsdr.uspto.gov/documentviewer?caseId=sn87980831&docI.... For that second one, looks like MS sold some assets to Meta after is shut down its Mixer service: https://en.wikipedia.org/wiki/Mixer_(service)

Apple does use X a lot in product names, but (i) the use is never on its own, so the comparison of the marks is, e.g., X vs Mac OS X, and (ii) Apple generally uses X to denote "10" so that portion of the mark is arguably descriptive or generic as a version number (see https://tmep.uspto.gov/RDMS/TMEP/print?version=current&href=...).