Earlier quoted context omitted.
This. Help the person you're interviewing. You'll both get more out of it, you'll both enjoy it. If you're in a company that is expanding, you'll be interviewing a lot, so it's really important that it doesn't depress the shit out of you.
There is a risk that you accidentally do the thinking for them and give the answers for them without noticing. Doing a collaborative interview requires careful attention by the interviewer, but I agree it’s worth it.
I've definitely had interviews with solid candidates who just faced an early roadblock, but were brilliant after I gave them an early push. Sometimes that's more of a sign of communicating a question poorly or nerves than genuine lack of knowledge on the candidates part.