Well I have to say I agree with your basic point. Of course, this thread probably isn't going to help many people make up their minds and most on here didn't need to make their mind up. The majority of posters on this thread knew how they were going to vote as soon as the election was called and the majority of those posters are Labour supporters (or at least left-leaning). There was a reasonable amount of criticism of Theresa May's interview this week and a certain amount of gloating when the other guy (Fallon?) screwed up over the Boris quote but very little said about Corbyn.
When it comes down to it, these interviews - and the debates when they happened - are somewhat interesting if you're into politics but not that important (at least not for me) because I don't think many people watch them or take that much interest when they do. The interviewees are usually more concerned with not screwing up than with saying anything significant.
Being able to interview well also doesn't mean you'd be a good prime minister. I won't be voting for Corbyn but I have no interest in criticising him for today because I think it's ridiculous to expect him to retain every statistic or piece of information in his head. When I'm at work I often have to tell people I'll need to check a figure or the exact wording of a rule or piece of legislation. It's perfectly normal. Similarly, I think it's somewhat silly to criticise Fallon (if it was him) for not recognising that the quote read out to him was something Boris Johnson had written however many years ago. Your response is a perfect demonstration that this is exactly the sort of petty point scoring that puts people off.
I wasn't point scoring, as I don't have a political allegiance to point score for.