Exactly. If there is any hardware platform that should be a "reference" platform for Linux (or FreeBSD) it should be the mac. It's a very tightly focused hardware ecosystem with broad adoption and of higher quality - inside and out.
It's a very tightly focused hardware ecosystem with no publicly available documentation for the ways that it differs from the broader hardware ecosystem. Supporting Apple hardware well is hard, and I say that as a person who's done a lot of work on Linux support for Macs.
There are a few reasons why a mac wouldn't make a good reference platform. Besides Apple changing hardware/firmware setups between every release, it doesn't have much official documentation and support for developers making an OS for it. Many people go to great pains to make linux run well on a Mac, especially hacking around the UEFI bugs that are present (not that they don't appear on other platforms either).
You also don't really want a reference plaform for linux, because as soon as you specify one, you might start making decisions which only benefit that platform. This is bad for the current eco-system, as it could impact linux's ability to run everywhere.
PS. Not to mention that Macs ship with broadcom wireless cards these days, which don't have very good linux support.
That's completely your opinion. I have had much better luck with Thinkpads. Many of the Unibody Macbooks have severe wifi connectivity and overheating issues.
As far as broad adoption goes, it may be more broad than the adoption of Thinkpads, but I wouldn't call it "broad" by any stretch. Mac market share is still quite low - less than 10%.
