I think the problem the author is referring to is it stopped being about Math and much more about impressing random strangers for the chance to gain an opportunity.

My experience is similar to you - I too really enjoyed my time doing these activities but once everything I ever enjoyed started becoming brownie points for my college applications, the competition started becoming "Grind X tasks and Y patterns so you can make the grade! Cause if you don't solve this in 14 minutes, then that kid will and he'll get your position!"