Lots of people like to say "A gun is a tool, like a hammer," and make other silly equivalencies like that, so here is a meme to undercut that.
Especially since - let's have some perspective here. A HOUSE isn't that big. It's got curves and corners. Most houses have paper walls that bullets will rip right through.
So, an assault rifle is about three feet long.
If I'm sneaking around my house, trying to find the assholes who have broken in, I don't want a three-foot long thing banging on the walls, and snagging on the corners, and blowing my stealth rolls. No, a pistol works much better for being stealthy, especially in the middle of the night.
Also, an automatic weapon shoots a shitload of bullets per second. Remember the paper walls? If I am not absolutely certain where every member of my family is, and where the dog is, then I do NOT want to be blowing my own house full of holes. Nope, I sure don't. If the intruder startles me, I might accidentally spin or twist, and suddenly I've put two bullets through the dining room ceiling, through my baby's crib, and not only have I failed to surprise the intruder, I've just killed my own baby. Yep, my husband and in-laws are going to sue the shit out of me, and my other children will never forgive me for being so careless and stupid.
I mean, for fuck's sake, how much brain matter does it take to realize "I need a big ass bullet blaster for 'home defense'," is such a load of crap?
(Note: I revised the text to remove references to the AR-15, since it turns out the AR-15 didn't meet the requirements for the point I was trying to make - q.v. comments below.)