Why are dome and nails not used anymore?

Because the way a dome and nail worked required it to be very hot.  With the new way of doing low temp dabs we have found there is a better way.

Also, clean up of a banger is easier than with a dome and nail.

What are the right temperatures for dabbing concentrates?

This really comes down to you, the user.  Some like it hot, some like it cool.

428 would be the perfect temperature that will get you full spectrum.  At this temperature all the cannabinoids, flavonoids and terpenes are vaporizers.

Learn more here.