Regardless of the quality of AD as a product (it’s mostly good but has a lot of questionable stuff…)

It has been the sole driver of LDAP + Kerberos standardization over the last 20 years, and has excelled in that despite its flaws.

For all of its faults, the Windows Server ecosystem is incredibly good at providing graphical configs for everything that you'll need for a small to medium sized business, and Windows servers can really survive a surprising amount of abuse. For most things it's at least acceptable, and on a couple of things (Active Directory with Group Policy, as well as RDP) it's best in class and very difficult to beat

Of course all of Microsoft's killer products were built at least 25 years ago by engineers who've long since left the organization and it shows. Microsoft is trying so hard to move everything to Azure so they can charge monthly for access, yet everything they build into Azure is somehow worse than the on-prem alternative and as they stop updating on-prem options and keep forcing more and more migration into Azure businesses are going to get more and more frustrated with the constantly rising costs and constant loss of quality. Oh and whenever there's another Azure outage it's going to be increasingly un-fun as everything migrates into Azure