I will follow your rules and assume it's a serious question.

For writers and earnings, only the first clap count from what Medium says. So 1, 5, and 50 give the same credit/money.

For readers, Medium uses the claps to assess how much the reader liked a story. They compare the number of claps to the reader's average number.

"When ranking stories, our system will evaluate claps users give out on an individual basis, assessing their applause for a particular story relative to the number of claps they typically give."

https://help.medium.com/hc/en-us/articles/115011350967-About-claps

I think 50 is not needed. They could go with 5 maximum, and it will give readers the same possibilities. But maybe they have data that shows 50 claps is a good number. Also, at this point, they're sort of famous for 50 claps, so maybe it's good to have people talk about Medium.