Windows Client Time Sync with Domain Controller(s) not working properly

Have a look at these artcles and see if they point you in the direction you're looking for:

https://docs.microsoft.com/en-us/windows-server/networking/windows-time-service/support-boundary

and

https://docs.microsoft.com/en-us/windows-server/networking/windows-time-service/configuring-systems-for-high-accuracy.

While what you're doing may seem functionally the same, the fact is that you're locking your domain joined clients into syncing only with those 2 DC's rather than the authenticating DC (the domain hierarchy), which is the intended design.

What if the domain joined clients are in a remote site that has a DC? Do you want them reaching across to a DC in another site to sync time? Or would you configure those clients to sync with their local DC? What happens if you add more sites and more DC's? How sustainable a practice is that?

What if you need to replace one or both of these DC's? Do you want to reconfigure all of your domain joined clients? Again, how sustainable is that?

You may be saying "We'll never grow large enough for this to be an issue." But what if you do?

My approach is to not deviate from Microsoft's guidance and best practice recommendations unless I have a specific reason to, or their guidance and best practice recommendations have been proven to be wrong, or they just won't work in my unique situation... which is to say that I rarely stray from their guidance and best practice recommendations. They built this stuff. They know best how to deploy and configure it. I'm not smarter than Microsoft.