You are right, DPLF is a primer. I stand corrected on that.
My point still stands. A primer is not designed to protect against degradation by strong solvents. That is what the top coat does. Even then, I would suggest rubbing almost any paint with a strong solvent like lacquer thinner will cause some degradation, unless the paint was designed to pass this "snake oil barker at a county fair trick"
The reality is that in many cities you cannot even use lacquer thinner anymore because of excessive VOC problems.
Saying a primer will not resist degradation by a strong solvent is like saying it will not hold up to sandblasting. In both cases you are doing something to the coating it was not designed to resist.
Does SPI advertise on this board? Are they a supporter of this forum? Sometimes I wonder if somebody somewhere is getting a benefit by constantly pushing this product line.