This is a really important point. I agree WFH and other forms of flex-time is a critical option in todays workplace, but it's not for everyone and everyone needs to be aware of your coworkers state of mind and capacity for self-discipline.

Sometimes it's just "hey...you seem to pretty consistently miss the early meeting...you good?" or "you know you haven't been hitting it like you used to...but you seem to be killing it in EVE Online". But I've been through an employee where it was performance falling off->odd behavior on calls->slurring incoherently on calls->intervention->short term disability. Fortunately, recovery can work and they're back. In the office.