People will always make up reasons if the tone of the conversation feels adversarial, but just spend a week in r/cscareerquestions to see the unfiltered sentiment: lots of people literally bragging about working 30 or even 20 hours per week as a full time employee, or who explicitly call out "slacking off" as a reason for preferring WFH. "Rest and vest". Etc.
I think it's pretty common that when someone says "nobody does X", that's shorthand for "there is probably a very small number of people who do X, but not enough to make much of a difference".
Sure, there are some people who abuse WFH, but I suspect it is far fewer people than Zuckerberg and Pichai suggest, and there are other, more important reasons for productivity losses. Reasons that have more to do with management and poor strategy than the actions of individual employees.
