It was a generalisation, but still mostly holds true, particularly for CDRs.
I wasn't knocking your theory, I subscribe to it myself.
My preferred writer is a really old Pioneer (think its a 108 from memory, certainly from that era). I'm guessing, due to age, for DVD media its using a default strategy, rather than an optimised one, but it still does an excellent job.
I've always had Pioneer, my first one was the A03 and it cost £800.
Write speed was 2x, and only with compatible media that was £10 a go. It didn't take long for the cheap media to appear, although this would only write at 1x and, quite frankly, was next to useless.
I use a DVR-216 for day to day DVD burning which I replace around every 4-5 months or so (because I knock the bollock$ out of them), and I have a BDR-203 for when I'm duping Blu-ray.
But the main point of my post was if you use CDRs in these changers, you will prematurely knacker your changer.
I'm pretty sure (although I guess nobody will ever prove it) that the manufacturers back then would purposely manufacture the changers so that reading CD-R media was very difficult.
I'm sure it wouldn't take much to tweak the laser bias to get it reading pretty much any sort of disc without any problems.
Newer head units of course don't suffer these problems, because the manufacturers have finally cottoned on to the fact that the end user wants CD-R compatibility at the very least when purchasing.