Required visual reference
alf5071h
In nearly all these types of events (and unfortunately a lot of the comments) there seems to be a basic ignorance of the meaning of instrument approach minimums, required visual reference, and what is needed to continue below DH or MDA.
ICAO Annex 6 is what governs the minima and they are based on a very specific requirement. Whatever the visibility, if you have not been able to confirm the aircraft's position and velocity in relation to the desired flight path from the external cues BEFORE you reach DH/MDA, you must go around. If you don't adhere to that, every aspect of the underlying safety assumptions is undermined.