The member's question raises very important theoretical and practical issues. As you anticipated, I'm well acquainted with the Levitsky–Ziblatt book. It is one of the foundational books in the recent spate of analytical books about the future of liberal democracy.
You've put your finger on the central argument of the book; namely, that if we look only at institutions and laws, and not at democratic norms that shape the way people actually behave within democratic orders, we will have missed something very significant.
There is a serious question, certainly serious in the United States, of what happens when all parties are determined to press their legal and political advantages to the hilt, to give no quarter to the opposition.