I don’t recall having an interview which was all competency-based questions, but I have had a lot have been 75-90% competency questions.
I agree with it being very hard to answer for people with little or no work experience (I had that issue a few years ago when applying for industrial placement roles). But I have a feeling that is probably intentional, a good way to discriminate against those with limited work experience, as I’m sure a good % of them would much prefer someone who they are pretty sure can start working with little or no coaching through the delights (or not) of the working day.
The HR people would say that as they have so many different interviewers they need some way of ensuring complete objectivity (partly for legal reasons), the only way they know how is to use competency-based questions.
I always struggled with questions like “tell me what you know about this co.” Of course I’ve done research and lots of reading in preparation, but is tricky balance between spewing out loads of different facts or just saying “I’ve read a lot of things about X plc this last couple of weeks and a couple of things that stood out for me were Y product is really cool etc.”
and like you I sometimes sat longing for a question where I could show them how much I knew.