To me, as a one who does not read first meanings or readings very hard, I don’t feel the priorities of meanings or readings one bit.
Of course, there are some meanings and readings which does not deserve blacklisting, nor they are perfect, and sometimes, none of the meanings are preferable at all – it is too nuanced. – You should notify the users on answering.
Also, primary meanings and readings probably almost always mean preferred meanings and readings, but it doesn’t allow multiple of such.
The motive indeed came from the イギリス and イギリス人 thread. Just putting in first meaning doesn’t really make be realize, and I don’t necessarily care that much about what lessons display. (I passed by lessons quickly.)
It can either be UserScript or official.