In an asynchronous-by-default working environment, there are few fixed sync points (meetings, pair programming, …), which makes dividing time between work and non-work tasks easier.
Some non-work tasks are essential (e.g. cleaning, laundry, taking out trash, grocery shopping, preparing food), but can be difficult to plan in a synchronous working environment.
When physically in an office, performing these essential non-work tasks can’t be done, and have to move to mornings, evenings, or weekends.
When working from home in a synchronous manner, performing these essential non-work tasks is hard due to scheduling constraints.
Having the freedom to decide when to perform creative work is important (see Offices and creativity are at odds).