Haha I'm really hoping I help you to understand, instead of confuse you. Please anyone more experienced in electricity correct anything wrong with what I'm saying. I think you are only grasping at one concept here. Yes it is true wire size can create a choke point for electrical energy, bigger wire can handle more current than smaller wire (generally speaking). However as the guys above have mentioned above the purpose of larger wire is to carry more current (amps) what the amplifier does then is convert that large current on the input side, into a smaller current on the output side, with a lot more voltage. The higher voltage on the output channel of the amplifier makes it possible to give the subs high wattage (a raw power rating), which is basically needed because your car is designed to run on (aprox.) 12 volts and that is not enough voltage to make subs go BOOOOM. The reason you can have smaller wire for the subwoofers, is because wire can handle a lot more volts than 12 very easily. The dangers of having too many volts on a conductor is the capability for that electricity to jump to another conductor through the air (spark) (the more volts you have the more unstable the electrons are and the more they move. The wire counteracts voltage dangers with insulation (usually rubber in car audio.) I'm not sure on the exact voltage that typical car audio wire can hold in check with it's insulation, but even an extremely conservative guess would be 600 volts, and you will never be going near 600 volts of output to your subs. I think my 1.2k amplifier is outputting like 37 volts right now to give my subs around 600 watts. The main thing to take away from this is that wire size is more for the amount of current (amps) and while the amplifier needs as much current as possible, the subwoofers do not, they take more voltage and less current, not requiring as large of cable. I hope this is all accurate and helpful. Feel free to read up on basic electrical theory/concepts to understand this more.
