When you put it that way, I guess you are right, but you should also consider we have m/Apple, a whole apple community and it's one of the biggest places on kbin.
MacOS doesn't have the same level of lock down as their mobile devices do. Apple also sets the trends so there's great interest in what they do, since their moves are those that other companies will follow good or bad.
I know, and I've subscribed to them early on, but my feed is flooded with other communities and I don't recall ever seing amything from /m/Apple...
I also just went there and the newest posts are mostly days apart from each other...
So "one of the biggest" might be true for the subscriber count, but threadwise not so much activity there.
Which is a bummer, honestly... I'm not a huge fan, but I'd still love to be up-to-date on their stuff.
Well, that is obviously because Kbin is new, smaller than something like Reddit, other communities that may flood your feed is mainly because they are generic, while m/apple is well, focused on Apple and it's products, it has more to do with having less users to post on a community that is more specific.