Sure, there's an argument to be made that if the seat you paid for has the option to recline, then you should be able to recline it. The problem is that most planes are designed so tightly that if the person in front of you reclines, now you have a stranger snoring in your lap for the entire flight. If you're tall or have long legs, forget about having any kind of a comfortable experience.
Now, a video of a man punching the back of the seat of a woman who reclined is morally dividing the internet. Repeatedly punching the back of the seat of the person in front of you is a wildly immature and rude thing to do, but some people are still taking his side out of anti-reclining solidarity.
The good news is: whether you are a recliner or an anti-recliner, no one is more annoying than a screaming child on a plane.