You're right, 'liked_by', for all, and button displayed for who 'can_like'. None of the two visible when the likes feature is disabled at forum level...
Checking it out: that's how it was, and it was perfectly fine.
https://github.com/eurich/Elkarte/commit/fe52ebdfdeaca80904f4e37f1fb00f01820a6bf2#L1R216