Why is the stock Android dialer app incompatible with my Samsung J7 2017? I want to install this app:

https://play.google.com/store/apps/details?id=com.google.android.dialer

to replace Samsung's customized dialer app.

But on that page it says:

"This app is incompatible with all of your devices."

Any idea why, or any workaround?
Some apps are only set to install on the phones they are designed for. The workaround is you can get it from apkmirror.com and install it. It should work on your Samsung. I installed it from there last year on my LG V20 and it worked fine.