[ninjin]

You are being overly defensive here. What I wrote had nothing to do with GNU in particular, as I hope I made clear in the very next sentence after the one you cited by stating that the same is true for BSD make implementations and portability. The parent asked about GNU make, thus I logically kept on talking about GNU make.

[tpoacher]

You're right, my apologies. :)

I misinterpreted the whole thread as "what's wrong with writing makefiles for GNU make specifically".

Which is subtly a different question (and to which the answer of course is "nothing, as long as you're happy to specifically use GNU make to run them").