It's not a court of law. The differences between a court of law and a congressional hearing, including the differences that would matter with respect to hearsay, are enormous. Demanding hearsay be excluded from a congressional hearing is as superfluous as demanding hearsay be excluded from a press conference or a message board thread. It's a trivial concern, a procedural impossibility and, as far as I know, has never been done in the 200+ year history of congressional hearings.
And if this is the first time Godwin's law has been invoked in this thread, someone is NOT being a good advocate for their cause. Yes, I'm referring to you, Disgo.