Yep, I’m with you on that. Unfortunately, I think the /r/pics mods are somewhat replaceable. That’s not to say they don’t do a good job - they definitely do, and I’ve got nothing but good things to say about how they’ve handled this last month. But it’s a catch-all subreddit without any real sense of community, culture or curation. A new mod team could be brought on and, after a short acclimatisation period, I think the subreddit would probably feel the same as ever.

There are definitely other subreddits that will suffer much more if they have their mod teams replaced because the mods really curate the content - setting posting rules, banning certain topics, removing things that don’t fit the culture of the subreddit and that aren’t at a high enough quality, etc. Replacement mods simply wouldn’t do it in the same way.

The fact that the biggest subreddits are like /r/pics - catch-all subs with somewhat replaceable mod teams - makes it very easy for Reddit to treat this as being less serious than it is for them. Yes, the big subreddits with the most subscribers and the most traffic are catch-all subreddits with somewhat replaceable mod teams, but those aren’t why people stay on Reddit. People stay for the curated subreddits, the special-interest subreddits, the niche subreddits. And those are the ones that are far harder to find replacement mod teams for, let alone ones that continue to keep the subs going as they were before.

How Reddit handles this open letter will be quite interesting. There’s nothing unreasonable about this letter and its requests. Like you said, if Reddit can address it satisfactorily, there’s still a chance things can be smoothed over between Reddit and moderators; a lot of mods don’t want to leave the site, after all, and are looking for an excuse to stay - that’s why there are still open letters being posted rather than everyone just resigning as moderators right away. But if Reddit doesn’t address it, and address it well, I think, because it’s so well-written, well-intentioned and reasonable, it will reflect terribly on Reddit and could easily be seen as the final straw by a lot of mods.