It still really depends on your hardware and the media used. The post even says for CD media that you should use 16-32x even though most modern drives allow 48-52x, so it's not applicable to CDs.
I used the same DVD media for years, a pale blue topped Datawrite Classic 8x DVD-R (G05) and then subsequently the 16x variant (FK1). The 8x discs always produced more consistent results at 4x, similarly the 16x discs did so when burned at 8x. That is just my experience using a few different burners yet using the same media, and I have burned literally 100s of these discs.
I pretty much stick to that rule now with DVDs, to burn at half the rated speed and rarely have had issues. I can definitely say that burning discs with a lot of small files (like an OS), that burning at max speed can sometimes cause read errors, even when re-reading the disc with the original burner. Also as was mentioned with CDs, that roughly half max speed is ideal. I can clearly remember my old Xbox1 struggled badly with any CD that was burned at more than 16x and point blank refused to read 40x or higher.
The reason burning slower is suggested is because most people default to max speed and they are more than likely using poor or average media. Burning at slower (not slowest) speeds does seem to rectify this problem in most cases.
Consoles were mentioned too and I think anyone that has burned a lot of games at various speeds will tell you that the drive sounds a hell of a lot more stressed when reading a disc that has been burned at max speed. Well at least that's what I have noticed. I've also found this with burning HD movies to a disc for playback in a PS3/360, that max speed burns are more prone to buffering, stuttering and out-of-sync issues.
I'd have loved to have seen actual proof of this theory in the post, like graphs from burns at various speeds, comparing bad burns, rates of error etc. Nice find anyway!