It's important to understand that not all acrylics are water based! Go into any halfords and pick up a can of car paint, it says acrylic on the tin, but spray it and it smells like cellulose!
The reason is that cars for years have been sprayed with cellulose and only in the past 5 years or so have the volatiles been phased out in favour of acrylics (think H & S and global warming) However as a manufacturer if you are offering a touch up paint that is going to be mixed on a car body it stands to reason it has to be compatible with the paint its mixing with!
So an acrylic bought off the car paint stand in an accessory shop will be compatible with cellulose and vice versa. Other types of acrylic may not be!