but cant you customise any distro yourself?
Yes, but that's not the same thing as "all distros are really the same" just to be clear.
Some folks would have to spend so much time ripping things out of Ubuntu or Fedora etc that it's much easier to build Arch with only what they want.
There are other benefits, but like everything else, not everyone cares about the same things.
If you feel like no distro does things the way you'd prefer, Arch may be for you. If you have no complaints about whatever distro you use, there's probably not any reason to jump ship to Arch.
Here are a few articles.
https://www.systranbox.com/an-introduction-to-arch-linux-exploring-its-features-and-benefits/
https://linuxiac.com/archlinux/