so is it safe to beleive that AD is multi-point approval system, almost for all applications, and tickets can be raised using it? So that means making another p

so is it safe to beleive that AD is multi-point approval system, almost for all applications, and tickets can be raised using it? So that means making another platform is rather obsolete, isn't? Also I have never used AD but reading its docs i came to know that, for using sso the company has to use the domain provided by the AD, like yourcompanyname@microsoft.com, what company will want its users to sign in using this kind of a domain?