In a word, Yes.
Primers are primers and paints is paints.
A two part epoxy primer is not paint. (so to speak)
It IS a super thing to have between your metal and your paint however. since they tend to be more flexible and have great adheasion properties.
Just cause some UV inhibitor is added to primer doesn't make it paint.. Primers tend to chalk up when exposed to Sun/UV over time. Inhibitors only do what their name say's
I have SPI Epoxy primer on my runner just to see what happens. It's been outside on the Oregon coast for nearly 2 years now and it 'chalked up' some already. I can rub it out quickly no problem but IT's THERE. I'd have to rub it out several times a year if I wanted a clean paint look.
