I disagree with that, certainly there's space for a slackware-like distro with a decent package manager. Debian, RHEL, etc. are excellent, but there's no denying that they do some things in their own special ways, for better or worse. But with most sysadmins used to some combination of FreeBSD, Debian, and RHEL, I doubt very many would spring at the idea of something new with no discernible benefits.
Like you said, most people using Arch are those who want a great deal of control over their desktop machine, but without the compilation and general cruft of Gentoo. And those will be the ones putting Arch on servers, I believe.
Any distribution is going to form it's own 'way' though. It's a natural side effect of having a packaging system in the first place - you have to start standardizing some things. Take filesystem organization for instance - after many distros fought over this for years we got the FHS. But there are still thousands of open source projects out there that each do things their own way and if you install a bunch of them on one system you're going to have a mess unless there is some standardization. Debian has its own way of doing things but it was developed over time, just like Arch is developing ways of doing things now.
Like you said, most people using Arch are those who want a great deal of control over their desktop machine, but without the compilation and general cruft of Gentoo. And those will be the ones putting Arch on servers, I believe.