Yes. Because it is their space. Period. For bags, laptops, legs, food, etc.
What dumbass selfish logic this is "I have the ability therefore its ok".
The person has the right to recline their seat. Your space begins where their recline ends. If they put seat in upright position then the allow you to use “their space” when they are not using it.
Personal bag is to be stored UNDER the seat. Not on your lap.
Seats are not meant to store all that crap. Just the passenger. I check my bag. Or are you trying to save money there also. Food? Other than a small snack in your personal bag why would you need to bring food on a 4 hour flight? They do sell snacks on the plane. Drinks too.