can't touch up PC, but you can with paint.
You can do paint yourself, can't do that with PC
you can do all the little parts at your leasure, not so with PC so easily
If corrosion gets under PC you have a real mess as large portions will blister, no so with paint.
PC looks thick and heavy on parts, no so with paint.
PC requires a ton of masking of threaded holes or retapping etc. not so with paint.
Good enamel paint is very tough and has worked for 100 years.
You touch up PC, oddly enough, with paint.
You can powdercoat small to medium parts yourself with readily available kits.
If you get corrosion under PC, it's probably from inadequate prep work by the shop.
PC probably does look a bit heavier than paint on smaller parts but it's usually the smaller bits that get handled more and the paint might be more vulnerable to damage.
The "ton of masking" is usually done by the shop and, really, if you're doing a frame, how much masking is there? Probably the same amount if you were going to paint it. Wouldn't you retap holes if you didn't mask them before paint, or would you paint without masking?
Good enamel paint is very tough. Powdercoating is tougher IMHO.