It was interesting to read this thread and glad to have found it. A lot of valid and interesting points raised.
I do wonder has parkrun become a victim of its own success? Parkrun was set up almost 19 years ago as a local community run by someone who wanted a bit of company but not the pressure of racing or having to go out hard. Now it has grown into something so much more, it has created a lot more work and expectation on individual parkruns. There's certainly an element of expecting "someone else" to do all the work, many people show up, run and go again. I've heard people say at my local - oh such a parkrun has pacers, such a parkrun has tea and cake after - but somehow they expect the RD or core team to organise that for them when they already have plenty to be doing. I will say the vast majority of participants are so nice - but certainly a good few don't volunteer or seem to understand that the event needs volunteers each and every week to go ahead. Like many other events, there are almost weekly shout outs for help and a lot of the same people volunteer much of the time. I think if parkrun focussed more on the "community" element rather that travelling the length and breathe of the country for the letter "F", there mightn't be so much pressure on the core teams.
I'm on the core team of my local parkrun, we get about 40-50 participants a week.