I recently flew delta from London to Seattle in economy class. There was a British guy sat at the back of the plane (his seat still reclined) who was telling the lady in front of him that she was not allowed to recline her seat for the entire flight! She told him that he was being ridiculous because it's a 10 hour flight and it's overnight so everyone will be reclining to sleep. His argument is that he is 6'6 and it's painful for him to sit in economy. It was also a full flight.

The flight attendant got involved and immediately told the man that it's his fault for not booking an exit row seat or business class. He told the man that it was the ladies right to use the seat that she paid for however she likes and if he doesn't like that they'll happily remove him from the plane and put him on another flight. The guy didn't like that but kept fighting. Luckily the seat beside the lady was a no-show so they made the guy switch seats with his wife so he could sit behind the empty seat.

Passengers are allowed to recline and you cannot force someone to not recline for your own comfort. The FA sided with the lady which proves the anti-recline argument is bs made up by entitled people.