There may be important considerations in favor of spelling bees that I'm missing, and I'd be interested in hearing any. I recognize that gifted children are often involved in spelling bees, and that there may be social benefits to being involved even if the activity isn't the most valuable in the abstract.
In recent years, spelling and geography bees have been dominated by Indians. When the winners are asked about their future career plans in media interviews, they often mention medicine. Medical school and pre-med classes require a lot of memorization. I decided against being a pre-med in part because I disliked the memorization in my 12th-grade anatomy and physiology class.
Lots of doctors in the U.S. are Indian, some having grown up here, some in India. I think Indians may do well in spelling and geography bees and in medicine because they are willing to do the intellectual grunt work of memorization.