Look - the simple matter of it is that this person paid for a seat on a plane. It comes with a reclining function. Some opt to use it, some don't. Simple as that.
There is no need to get vulgar or mad at a basic function of a reclining seat - reclining.
The reclining seat on an airplane is designed to be reclined - it has 2 modes: upright and reclined, at the passenger's preference. Its usage is not a safety feature, it's an option built into it and the price you pay for the ticket.
If you are bothered by it, you can always recline your seat and reclaim your space. Literally.
I cannot open a laptop, because that "relcaimed" space behind me is not the same type of space and is frankly useless to me.
Your argument is why humanity is becoming less civil and intelligent. People aren't thinking. One person shouts, so everyone around him shouts. Now everyone is shouting. The correct answer would have been for the loud moron to speak at a lower volume.
And finally, your argument fails because the last seat in the airplane usually cannot recline. So if you want to be fair, that precludes the person in front of him from reclining, and so on to the front of the plane.
Ergonomics of in-flight entertainment screens are not a concern of mine if I am trying to sleep or be comfortable. Take it up with the manufacturer or the airline if you've issues with it, not the person using their seat as designed.
If your personal usage of a laptop was an issue, it would have been addressed at the design stage of the airplane. You are flying economy, therefore you don't get the special treatment. Either upgrade to FC or accept what the rest of us peons deal with - cramped spaces made slightly more comfortable with a reclining seat.
As for the "your argument fails" part - same with the front passengers, who don't have anyone reclining against them. You pay economy, you get economic space. It's just how the world works. I've been there plenty of times, and there's nothing I can do about it - I just accept it. The world is not fair.
Front-row seats and exit row seats are paid upgrades because of the extra space. They aren't paying economy - they're paying slightly more.
I'm going to give you an acre of land. Would you rather have a square 208 feet on a side, or a strip 1 foot wide by 43,560 feet long? They're exactly the same amount of space!