AD DS is just quite nice to use, its mature, its been improved over the years. It has is sticking points but it works well.
If you have any windows servers or computers in your environment, AD is a no brainer. Which is why Windows server is seen a lot in environments.
I’ve worked in environments that have been 100% Windows, 100% (ish) Linux, and a mix of both.
Theres a discrepancy in the Linux one there. I’ve worked in an environment that was for all intents and purposes 100% Linux based. Except the workstations, the issue was that Linux just wasn’t capable of providing the end user software that was required for the users needs. In the end the servers were Linux, the zero clients were even linux, but the workstations that loaded onto them were Windows.
As for other environments. For a lot of things, windows server is just pretty easy to use, not only that but for office environments where you may have a mix of workstations, email, intranet, and cloud services, windows server, AD DS, and Azure and just great frankly. And Linux doesn’t compete.
In saying all that, even then, public facing web services tend to be a mix of linux or windows, product application servers are again (depending on technology needs) windows or linux.
It is at the end of the day, dependant on requirements and needs.
As for why people recommend it in homelab, I expect its because a lot of people run Windows, and windows server will be a familiar and easy to integrate environment.