My son is 8yo and plays baseball and basketball.
Don't keep score in T-ball...it's pointless anyway.
Other than that I'm for keeping score in all sports all the time. They always did when I was young.
This all reminds me of when we met my boys kindergarten teacher for the first time.(group setting) She said not to just let your children win when playing games. She has had many problems with children who couldn't handle losing on the playground. Then it becomes the teachers problem in the class room.
BTW, we never just let our son win at games. He had to win them fair and square...and he many many times.
We as a society are not preparing our children for the realities of life.
All this being said...all the age appropriate rules must be in place to keep the game reasonable and also conduct rules for parents and coaches.