Milking looking busy in an office is just part of working in an office, most people don't even realise that's what they're doing. It's just what they've always done, and what everyone does.
Tea breaks/gathering at the cooler or kitchen, having to "discuss with colleague", walking quickly round so people think you're doing something important, looking focused at your computer when you're not really doing anything besides daydreaming.
This is why people are more productive from home. They are less distracted and working more than in an office.
I'm sure that some people milk it, put their washing on during a break, overrun at lunch... But not half as much as they milk all the distractions and "looking busy" in an office.
It's easier to pretend to work in an office than at home, because you just need to look busy and productive... Not actually be busy and productive. From home, the proof is solely in the pudding, so you have to actually do the work.
I think that's why a lot of people are actually afraid of the rise in WFH. They'll be outed as useless and unproductive, with no mask of observable "busy-ness" to cover their ass.