13 instances of "manual intervention required" over 6 years seems awesome.
I think I did 2 manual interventions during my time using Archlinux, and each time it took maybe 2 minutes, it was just a matter of copy-pasting the commands in Arch News.
Meanwhile you can use RHEL or CentOS and basically leave the thing alone for 5 years.
Distros targeting the same desktop needs are Ubuntu, Mint, Debian-flavors, Fedora, Gentoo, ...
In corporate environment for critical software you would get a contract with an on-call duty and you would only have a limited choice fo supported distros.
There is no defending it, it's a fact of life. You get bleeding edge at the cost of stability.
I probably wouldn't recommend Arch for corporate environments, but at this point I feel I should point out I wouldn't recommend Linux either if you're working in a windows shop.
I've had various non-rolling distros fall apart on all sides within 6 months. With Arch I've had one manual intervention(aka one copy-pasted command) in over a year and one minor issue where I needed to restart a service. That's amazing and something I'll gladly take in exchange for painless and straightforward setup of pretty much anything.
Not to mention with regular backups(that should be done either way) and delaying updates in critical time periods you can easily minimize the risk.
That's the minimum that you should be doing regardless of the OS. And thus, that's not where the risk is at.
It's probably more difficult to understand if you get paid regardless of whether you can get meaningful work done.
But for those of us who live on the other side, losing an unplanned half a day due to an OS issue that actively causes us to lose money, it matters.
Arch is bleeding edge, this means software bugs are far more likely on it.
That said, just because you had good luck doesn't mean that it's stable.
Here's the most trivial way I can think to explain this:
Check out Arch News.[0] Ctrl-F (Find) 'manual intervention'. Six years of results on the first page ; 13 instances of 'manual intervention required'.
Reliability != stability. Stability usually implies a platform on which one can use and develop for without expecting common major changes, if ever.
As for the anecdote of using the [Testing] repositories, a users experience with such things really depends on their use of new and currently developing software.
A simple computer with simple peripherals that is used to run emacs all day isn't likely to be broken by the Testing repositories.
Personally , my anecdote : the second someone starts using Arch for something new-fringe (hi-dpi, touch, tablets, SPDIF, SLI, NVRAM, new window managers, new x-windows replacements, prototype schedulers, filesystems, or kernels, PCI pass-through, exotic RAID configurations..) [Testing] repository is an act of masochism. It's only a matter of time before something drops out.
I found that my best bet was chicken sacrifice and Opus Dei-style self flagellation before each [Testing] 'pacman -Syu' . At least then I had a 50/50 chance of the next boot. But, granted, I use a lot of weird or fringe hardware.
All that said : other distributions don't have better [Testing] repositories. It's just that [Testing] is for .. testing. It's unstable by its' very nature.
[0]:https://www.archlinux.org/news/