A BD-writer focus on BD and not on DVD. Same like DVD-writer focus on DVD, not on CD.
I have/had some exotic media and note that BD-writers don´t support em like the older DVD-writers or CD-writers. Maybe to save time and work, maybe because the flash for firmware isn´t big enough.
At least, the last 24x-writers support only 2 discs at 24x, like TY or MCC. All other media is max. supported at 16x, except with some Pioneer. Older 20x, 22x and 24x supported higher speeds than 16x with more media