What if I back out of a parking spot carelessly and drag my front bumper all the way down your passenger door. Your door still works fine, but now there's this huge scrape down the side. Would you care? Your car still drives fine; it does all the things that a car needs to do to be useful.

No, you would not be ok with that. Why? Because you don't want to look at a big old gash down the side of your door every single time you get in and out of your car, and it greatly decreases the value of your car.

It's the same thing with neighborhoods. You can park an old dead El Camino in your front yard and my house still does everything it's supposed to do. It keeps me warm and the rain off of me just like it always did. But I don't want to look at that dead El Camino with weeds growing up through the engine compartment every time I go in our out my front door, and it reduces the value of my house.

I guess it's a NIMBY (NIMFY? NIYFY?) thing to not want to live near unpleasant things. I don't know what to tell you if that baffles you.