Now back on to the topic!
It is not only "weekend pilots" that make too many calls, but charter and regional airline pilots are "offenders" but perhaps for different reasons.
Certainly the lack of any STANDARDISED training in R/T is a very significant reason for so much verbal garbage these days. Many instructors and training pilots teach what they have been taught themselves and without a specific course that is examined there is very little if any standardisation from the flying school to the airlines. Even many airline pilots talk too much. Just listen to the excessive readbacks you hear these days! (you could have a thread on that alone!)
As for operations in a CTAF (or MBZ) the very basic philosophy should be that you only conduct direct exchanges with traffic that is in (potential) conflict with you (in order to avoid that conflict). There is absolutely no reason whatsoever to talk to everyone that you hear in the CTAF/MBZ just because they are there. If they have made a broadcast in response to your initial call and they are not in conflict then that should be it.
Of course the problem mentioned above in regard to training might prompt an unnecessary exchange if the required information is not provided in the broadcast. (ie: position/altitude/intentions etc)
In an ideal world an initial call (inbound or taxi) should prompt a broadcast from anyone else in potential conflict. If there is no conflict expected as a result then that should be it - period. Any subsequent broadcast should be recorded and assessed for conflict in a similar manner. Only if a conflict is apparent should direct communications take place.
Some of the worst offenders are some regional airlines who seem to teach their folk to talk to everyone they hear even if there is no possible conflict whatsoever. A certain Saab operator is a big offender in this regard. Of course what happens next is that Joe Private Pilot hears all this carry on and thinks that it must the right (??) or done thing and tries to copy it without the background knowledge of what he is trying to achieve as a result. All this only adds to the garbage and makes the problem even worse. #$%^&* !!
As was said in an article some time back, one should consider what "value" is obtained from any radio call. If there is no value, then why make the call?? Of course the exercising of some common sense and good airmanship to all this would also help. Trouble of course is that neither of these items is found in the training world these days. CASA and ASA don't seem to understand the issues either, otherwise they would be addressed - no?