Thanks for the write-up @Dominic . I don't think it's worth removing them given it's not clear what the benefit would be.

Thinking about posting private messages to ones self reminds me of how DNA is - there's a massive amount of 'non-coding' DNA in our body. Some of it seems to have expression regulation function, other parts of it just seem to form buffer which makes it less likely for the chain to be corrupted - because point mutations (corruptions) are more likely to happen in non-coding areas ...

Maybe there's a plugin which just sprinkles private messages in response to random message arrivals... and maybe we could also store useful info in those ... like I could cue up my dotfiles / config files to be regularly posted to myself as text in those messages...