You can earn hats on https://meta.stackexchange.com.
I have Like Clockwork:
Because meta sites (per-site meta, not this one) are not real Q&A sites, but rather "children site" of their main site.
They have no reputation of their own, no users of their own, it's all taken from the main site, hence the hats are also taken from the main site, and are not independent on the meta site.
Some hats in previous years did require meta participation, as mentioned in the answer to No hat for silver badge on meta, for all we know this year we might still have secret hat involving meta.
All in all, this is a valid decision in my opinion, since most meta sites have very little activity there's no real point in having independent hat system for them.