I'm not going to rehash a lot of the points that people who are much more articulate than me already made. Ultimately, the trend towards gatekeeping of events is one that disturbs me because like many, what drew me to long distance running was the inclusivity of the sport and that you don't have to be an elite runner to participate in these events.
Ultimately, I think there's room at rD events for all types of runners - from those who want to run fast and PR to those who are there for the experience. What's more important than where you fall on the continuum is having respect for other runners and knowing how your race impacts them. People walking or running 4 across on the GF walkway doesn't make it a great experience for anyone. Where rD could do better is really overemphasizing race etiquette given the number of first time runners and increasing the number of corrals requiring POT to better spread out the field. That being said - it also goes back to my point about showing respect for your fellow runners. I have a B POT but I am not running out of B at my race pace- so I won't start from the front and I'm hyper aware of faster runner at the start.
I also think this all started with some improper assumptions based on incomplete data. In the original reddit thread, they talk about a 19% DNF rate. Assuming the stats are correct (big assumption) - for rD it's 19% of registrants who don't complete the race - so that combines DNS and DNF. As far as I can tell, very few major marathons publish the number of registrants. They compare finishers to starters. There's anecdotal evidence that rD races have a very high DNS rate compared to other races. And while I believe rD has a higher DNF rate, I doubt it is anywhere near double digits. As others have pointed out, other races acknowledge that they factor historical DNS rates in how many registrations they accept. I'm certain rD does the same. So while those DNS registrants are fighting with us for queues on registration day, they aren't artificially reducing the number of available bibs.
I'll also echo this is one of the reasons I like this forum - we can have a conversation where we don't all fully agree without making it personal.