Currently, public sub counts are abbreviated in most but not all places across YouTube. In August, we’ll make this more consistent by always showing abbreviated sub counts publicly. Creators: You’ll still see your full sub count in Studio! Learn more → http://yt.be/help/abbrev-count …pic.twitter.com/pmaKk4EU4k
That's because whenever one wants to set one up, they get snuffed out by YouTube or Google claims parent x y or z on the sites layout, it's a monopoly at this point, which is an issue on its own. So I'm reality, YouTube can do whatever it wants BECAUSE there's no other option.