Well, I spent the morning riding a black bike, wearing black longs, a black jersey, and a black woolly hat, and I don't think that's plain daft. I was visible, just as the many pedestrians I passed wearing black clothing were visible, and the black cars which I saw on my ride were visible.
I do believe that hi-viz makes you more visible. I don't believe that it's necessary to be any more visible. When it gets dark I stick two whacking great lights on. If a driver doesn't see those, they're paying no attention, and won't notice hi-viz either.
I used to wear a lot of hi-viz clothing (I still have some truly cringeworthy flashing hi-viz armbands
). I don't wear hi-viz now because when I did, I got so much casual abuse off car drivers that I was seriously considering stopping cycling. When I ditched the hi-viz and helmet, it suddenly stopped, and cars gave me noticeably more room.