That's a very good point. Personally, I prefer to do as much of my smithing and repairs on my own, but the easiest answer with a factory AR is to let the mothership solve the problem they created. Even if I DO send a firearm back for repair or replacement, I like to know what should get fixed when it gets there, to be sure it actually gets fixed.
There are two downsides to sending one back to keep in mind: 1) time in transit - if it's a simple mag problem or fouling/lubrication issue, a good cleaning or a new mag will get it running in a matter of minutes. Most major manufacturers will have you without your rifle for a few days of shipping at both ends, plus at least a week in house, sometimes longer. I can usually identify and fix any issue within an hour, so I don't like to send stuff back for a couple weeks if I don't need to. 2) their test ammo may not match your real world ammo - if they run high octane test ammo and it runs fine, they'll send it back and say all is well. You'll still have a problem with your ammo when it gets back - then you'll get frustrated that they didn't do anything and it still doesn't work and maybe send it back and the same thing happens again, or maybe on the 2nd or 3rd trip they say to send some of your ammo back with it... months down the tube (item 1), and they still didn't fix anything yet. This usually ends with an online thread (or dozens) where the owner bad mouths the companies customer support and swears off the brand forever, whereas it's a simple issue of differing ammunition selection...
But overall, the easiest route will be to send it back to the mothership to let them sort out the issue - just be aware of the two items above, and don't turn into "that guy" who swears off a great brand simply because they're running lighter ammo than the rifle was designed to use.