BH should not exist at all! Authors should give enough clues and hints to solve each one of them.
I'm sorry Arunas, but I tend to disagree. Without the Black Hole, we would now have 16 pages of Professional puzzles, most of them laying dormant for many years (we already have Pro puzzles that haven't been touched since 2016), but far more unmanageable.
At least with the BH, when puzzles
do get solved (as a few long-term BH puzzles have within just the last few days, proving that the solution is always out there somewhere, but can sometimes take a while to find), the puzzlers are rewarded with a least two points for their efforts.
To help reduce the number of unsolved vehicles within the BH, perhaps we could consider reworking BH. For example, we could reward the puzzle placer with a point if the puzzle has not been solved within the first two years, two points for three years, and so on. If a puzzle reaches its fifth anniversary unsolved, perhaps the puzzle placer then reveals the full details of the mystery vehicle and is awarded five points, for example, just as an idea (as an example, I'd love to know the identity of the 2CV/GT40 BH puzzle that PJ posted in 2010, as I have spent many hours - if not days - trying to find the answer to this one!).
After all, we are all meant to be car experts and enthusiasts here, so the puzzles should not be too easy and obvious, otherwise we might as well just post pictures of VW Golfs and Maserati Khamsins all day. Maybe this is one for the AP Masters to consider?