I can do crap like respond to emails, make todo lists, read documentation, write specifications, and google for the solutions to known problems. I am however fortunate enough to have a job where all that makes up a minuscule fraction of the work I do, most of my work is in solving new problems by developing and implementing algorithms. And that requires thinking on my part which is something I am completely unable to do with new thoughts about my changing surroundings constantly entering my head. My work provides two person offices with enough space to be comfortable. As well as common areas where you can work if you so choose to be out in that type of noisy environment. Only a handful of people make use of the common areas for anything besides eating lunch or having scrum.
I believe it is because nearly everyone's work involves either thinking or being in meetings all day. And while I will not be supporting it I believe if you give someone who needs to think the choice between a nice quiet office where it is accepted that if their door is closed you don't bother them, or a nice common area with the noises of people walking by and milk being frothed, they will eventually realize they are more productive where there are fewer distractions. (Not that everyone wants to be more productive)
You seem to have a righteous indignation about people doing what you've described yourself as doing.
This is why I, and many others like working in coffee shops. There's usually an ambient background noise which makes it feel like you are involved in something, but it doesn't require your direct attention. I think there's also a subconscious element to having activity around you which keeps you focussed. I personally find it easy to look at cat videos on the internet when no one can see my screen, but when I know people might walk past me when at a coffee shop, or at work, it keeps me focussed.