I think you misunderstand the display put on by most senior members. They have staff that can get details. However, playing dumb or obstinate is a negotiating tactic. The authority hierarchy at play is more important that the details of the tech, viewed a certain way. Let's be blunt, more than half of all representatives in both parties work on behalf of local, state, Federal and international security.

And many of them - on behalf of foreign nations.

It's not just lack of knowledge, but lack of willingness to learn and apply it.

Their priorities are set on the power plays that happen in government chambers, the government and corporate interests that ask them to change laws for some purpose, and performing actions that will keep them elected (in that order). Banning encryption is something that satisfy the second group, where government organizations would love to make their jobs easier by having a key to encrypted communications. The fact that the entire internet is built on encryption is only a barrier to these governmental powers telling lawmakers to "pull the trigger" on banning encryption, since the compromises will hit corporations the most (since corporations actually do need perfect encryption without the government spying on them).