If I have a child under 2 on my knee and you recline into my space, restricting my space and the space of that child, you might feel the movements of that child, since the space has been restricted by you. I am not responsible for the problem that you created by restricting my space. I obviously wouldn’t encourage it, but it’s a natural consequence.
Plenty of things are allowed and normal, but are also selfish and frowned upon. Farting in a lift, listening to your podcast on loud etc. All perfectly legal but irritating to others and impact on their experience for your own comfort/enjoyment.