I get what you are saying. But for some folks even few days per week of avoiding commute hell and general dreariness of office is better than everyday at workplace. I'd be happy if my employer allows that.
Sounds like teams (and other job factors), not individuals, decide which days will be in-office. The post says: “your product areas and functions will help decide which days teams will come together in the office.”
I don't think these companies have thought this through. Logically, the 3 days a week in office will slowly become 2, then 1. Or maybe teams will decide to only get together 3 days a month or something like that.
At that point, you're effectively fully virtual anyway.
These companies need to just dive right in, because the suggested format smells of poorly thought out compromise.