I'm a SLF. If some poor bastard in a single-engine prop with 100 hours and a Mark I eyeball gets lost in the UK and calls a practice pan, and recovers without anyone the wiser, you think he's polluting the frequency? Maybe YOU guys in heavies with a ton of nav equipment need a new frequency together with an OBLIGATION to answer within 10 seconds or lose your commercial license.
Your first point is quite valid. Practice or real (and sometimes there is no distinction) that is part of the frequencies
raison d'être. A new secondary universal frequency would be fine if that reduces the clutter. It doesn't really matter who has to make the change.
121.5 as part of the safety protocols, now needs mandatory monitoring. It is a safety net and provides a secondary layer of protection from PLOC events as one of its functions. It is the level of distracting and unnecessary babble that is frequently causing it be tuned out. When that happens the secondary protection is gone. This whole issue needs to be properly addressed by ICAO, and improvements and changes implemented as soon as possible. The system as it is, is no longer fit for purpose and hasn't been for quite some time. The poor situation is only exasserbated by the few who use it as a playground or arena. The facility needs to grow up, as do a few of its users.