Per How does the EU General Data Protection Regulation (GDPR) affect MusicBrainz data - #5 by rob MusicBrainz could also remove birth month and birth date (but not birth year or birth place?).
Most of the time, editors add legal names, birthdates and places without sources, and then everyone just copies the unsourced information, regardless of whether the original data could be verified or not before it proliferated throughout user-edited websites. I would hope reasonable editors wouldn’t vote against removing data that has no source and low expectancy of accuracy (i.e., the removal of guessed Japanese name romanizations).
Voters are supposed to assume editors are acting in good faith (bar sustained malpractice).