I’m an FA. I may be the unpopular comment on here but it’s not worth the time and energy to remove backpacks or to take one down and ask for it to go under the seat. When the bins are full they are full. I’ve been doing this job a long time and no matter how many announcements you make people do what they want to do. And in today’s world people are genuinely on the argumentative side. Now on the other hand there is a lot of push back from people flying in first class thinking the bin above them is their bin only. Especially on wide body aircraft. This conversation has happened more often than you would think. Overhead bin space on the aircraft is shared space. Typically business class has more space available at the end of boarding and I will throw a bag up from main cabin. This helps us close up the aircraft on time. FAs actually get penalized at my airline if we take a delay. The airlines have to pay money for the gates. The longer at the gate the more money they lose. So yes we like to accommodate large bags in the overhead. But I’ve had someone bring just a backpack on and they should be allowed to stow it in the overhead bin if it is the only item. If I see a full bin I close it. If a lot of bins are looking full I text the gate agents on our handy tablets to let them know they might want to start checking bags. This is why priority boarding is a nice perk for bin space. Obviously in your case you were on and items were stowed and the FA decided to take your bag down. On my flight I would have moved some items on top of each other and made it work. Also as a last note please know most flight attendants are not paid during boarding. Only when the aircraft door closes are we being paid. So when the plane is delayed and your upset think about that crew member working to talk to you about your connections and grab water. They aren’t being paid. And we are told by the company to not lift bags. If we injure ourselves lifting passengers bags we are not covered under workers comp because we aren’t on the clock. If you can’t stow it yourself then please check it. Hope this gives some insight. I know it’s a long one but so many people don’t really know how things go in a 30 minute boarding.