Amazon says workers need to be in the office. Most of Silicon Valley disagrees

I have no strong opinion on return-to-office, but your argument addresses the maximum achievable productivity of a worker, derated by those factors (noise, etc) that effect your individual productivity. An argument against work-from-home is that (a) few workers achieve maximum achievable productivity in any environment; and (b) averaged across the spectrum of workers, the negative impact of reduced observability and accountability is at least comparable to the negative impact of the in-office work environment. Depending on how these influences balance, secondary effects (hallway discussions, investment in commercial real estate, whatever) can become the deciding factor.

Individually productive, 100% no argument there from me, people work better and quicker at home.

Collaboratively productive… remains to be understood. We need a collaborative tech breakthrough to push remote productivity forward. AWS Chime is awful and they use it very extensively. MS Teams is awful. Google’s Meet is subpar. Asking for certain work to happen remotely is just not going to be as fruitful as in person.

Those daily long lunches were time/place where on rare occasion ad-hoc discussions would lead to a new way of doing something, a new (micro)service ...

Basically the type of synergy/innovation that is typically thought by business that it happens by the water-cooler.

On the other hand, in my experience and observations - just one or two of 2-3 days hackathons (so total of <=6 work days) produced almost an order of magnitude more synergy/innovation than those daily (long) lunches during the rest ~5 years of workdays.

Though sure - some things like initial employee onboarding (or even internal move to different unit/team), trainings/workshops, (semi)annual or quarterly plannings...etc are usually better in person.

Yet I've basically never had any of those at office desk. It was either bigger conference room (or dedicated auditorium/presentation/workshop room), or a meeting/lunch with manager or a (more) senior person with one or two of "newbies".

After initial onboarding (which is usually a week or two of "newbie" not being at desk with the rest of their new team).

All of those things add up to 1-2 days in office per month (including giving talks/training/workshop to "newbies").

Add 1 day for interviewing candidates F2F, and we're up to 2-3 days per month.

Even if you have a hackathon each month ... And the most I've seen was 2-3 days once a quarter, though usually it was 2-3 days per half a year - so nothing close to mythical Google 20% of the time ... We're still talking about at most 4-5 days in office per month.