Voltage regulator VS voltage divider?

I want to make a few of those altoids oh sh*t USB chargers. Instead of using the 5V regulators like everyone else does, can't I just create a voltage divider with two resistors?

Why though? As long as my Iphone is seeing 5V it shouldn't matter, no? Or is the regulator really some kind of current regular aging device too? Dun think so.

And what are the odds of me destroying my cell phone? You think there's circuitry protection of I screw up the polarity?

I have no idea what an altoids oh sh*t USB charger is. However, I can tell you why a resistive voltage divider won't work, it's because the voltage at the output of a voltage divider decreases as you draw current from it. A voltage regulator as its name suggests tries to keep the output voltage stable (=regulated) no matter what current is drawn from it.
So if you make a voltage divider with 2 resistors and its output is 5V with no load (nothing connected), as soon as you attach your phone to it the phone will draw current which will pull down the voltage until the voltage is so low that the phone is only drawing a very small current, probably not enough to charge it.
You could minimise the voltage drop caused by the phone by using low value resistors but then most of your energy goes into heating up the two resistors and very little into the phone. Buy a regulator, they are cheap.

Is there circuit protection if you reverse the polarity? I wouldn't count on it. From the point of view of the phone manufacturer it's a lot better if the phone dies if somebody uses a badly wired charger, because then they have to buy another phone.

To produce 5 volts from a resistor voltage divider under load, requires an exact match to the current needs of the circuit - which can be done in a fixed circuit but certainly not in a phone charger - you are likely to destroy your phone or if you luck out, some other device you try to connect with different current.