It was absolutely not the case two decades ago. There were no other options for an enterprise fleet, 20 years ago, if the question was asked. If you weren't Google (who never asked the question anyway), the answer for managing 25,000 endpoints was to use Windows devices with Active Directory as the management plane. Anyone doing anything else was in for a world of hurt... and that's why every enterprise ended up on Windows, and why everyone targeting enterprise management targeted Windows -- because that's what the endpoints were already running.

What killed AD & GPO was Microsoft, in their bullheaded push toward Azure everything. Instead of listening to what it was that the enterprise customers actually wanted, they designed a system that made sense to them, but to no one else. The original UI was written in Silverlight. It was horrific.