Reading the GNU coding standards was what convinced me to move back to OpenBSD, after having had to move back to Linux for certain software support which is no longer an issue. In particular, this paragraph:

Quote: For instance, Standard C says that nearly all extensions to C are
prohibited. How silly! GCC implements many extensions, some of which
were later adopted as part of the standard. If you want these
constructs to give an error message as "required" by the standard, you
must specify '--pedantic', which was implemented only so that we can say
"GCC is a 100% implementation of the standard", not because there is any
reason to actually use it.

It reads to me both as quite immature and as something of a "Microsoftian" attitude. Every time I see GNU code I find it offputting, and I wouldn't even really consider myself a UNIX purist.