Real reason for the hate: The Linux community is overly focused on tribalism and has a console-wars mindset where what I'm using is obviously the best and everything else must be flawed and terrible. Manjaro is probably fine for most use cases.

...although I'd still suggest just using base Arch instead. :)

I think having a noscript site like old.lemmy.sdf.org available could only be a net positive, I can't imagine that it would hurt to have it as an option, as long as it's not too much work to keep it running.