Civil law or Roman law relies on written questions and answers, instead of live cross-examination. Citizens of continental European Union states, most of Latin America, most of East Asia, and several other countries suffered trial unconfronted.
The Framers were aware of the tendency for authoritarians to destroy liberty, under the pretense of national emergency. In the decades preceding the Revolution, British prosecutors instigated the practice of securing ex parte affidavits and offering them as evidence in “State Trials” featuring charges of treason against the Crown. Defendants were executed, never having cross-examined their accusers. Our Founding Generation was dealt similar cruelties in the 1760s. Parliament essentially declared martial law and vice-admiralty courts descended the colonies into Civil Law.
This right has endured relatively unmolested in our country. However, the practice of substituting face-to-face confrontation with video camera technology is beginning to emerge in American courtrooms.

Remember that armies train Soldiers to process captives by segregating, silencing, and speaking to them only to give orders. Research the Milgram experiment on obedience to authority figures. Imagine what a courtroom would look like if Government could separate the accused and the accuser into different rooms, where the accuser cannot see the accused. Under these circumstances, think of the willingness of an accuser to obey an authority figure who instructs them to perform acts conflicting with their conscience, like lying. Guess how effective your counsel will be at impeaching deceitful accusers, when those liars escape the pressure of the judge, jury, and the public in the gallery reading their body language. Reckon how fair a trial you would get under this system. Now suppose how embryonic single party rule might want to take care of some of its dissidents.