I recommend that anyone who is really wishes to know about what or what not, may bring about such as has been speculated on in this thread learn what the basic components of automotive paint are.
Once they search out this information, they may just stop speculating and throwing out "guesses" based on incorrect or mis-information.
Base to start at, "what is the resin system?", what does it do?
Be it an older lacquer, enamel or 1K or 2K or newer water borne or solvent based, be it an expoxy, etc.
The resin system is the key that holds everything together.
Attack that and most of what has been speculated about becomes much clearer.