I took part in math competitions as part of a math club in High School during the 70s. It was fun, made me think and was a bit of a social outlet. I don't think any one test was that important - we took a bunch of standard and experimental national tests and monthly meetups had their own problems.

All that said, my impression is current math clubs and competitions have been taken over by kids just wanting credit for college rather than the kids of my era, who were there 'cause they actually enjoyed math.

If the only purpose you can see for math competitions is find a few very talented kids, yeah, well then they would qualify as counter-productive.