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. :)
One distro that I’ve recently found runs pretty well on older/slower systems like this is wattOS. It’s a distro focused on power efficiency, but because of that it does well on underpowered systems.