i agree with you that strictly following the rules there should be zero non relevant communications on this frequency , as well as on any other atc frequency except 123.45.
i just told you that work in a cockpit is not perfectly sterile and humans are doing this work.
not a single time in my career i experienced a scenario somebody has real troubles and asks for help on 121.5 and somebody else spams and blocks the frequency in this moment . any controller in radio contact would in such a scenario tell such a dumbass to shut up immediately or face serious consequences.
when there is no emergency a quick talk about results is ok and accepted , any other opinion is really debating a pure theoretical worst case scenario by impressions from scanning live atc thru internet.