It’s just a linguistic phenomenon. In English, at least, the prefix meta- denotes not only a single level of metaness (if you will) but also two levels or more, e.g., meta-metaclass → metaclass. So the “closed loop” is there only for convenience, like saying “and so on”.

If we were being precise, we would explicitly denote the level at which we were working. However, we tend not to do so for two reasons: first, that we rarely work with n-meta things for high n; and second, that being explicit is just plain unwieldy.

It’s for the same reason that we follow line, square, and cube with 4-cube, 5-cube, &c.