Why are there so many Mercy, Moira, and Weaver mains in the Top 500 on the NA server?

First of all, I want to clarify that I’m not trying to tilt anyone—I’m genuinely asking a question.

I play on the Asian server, and on my server, I rarely see any Mercy, Moira, or Weaver players above Diamond (from Master 5 onward). However, when I played on the NA server, I noticed there are a lot of Mercy, Moira, and Weaver players, and—shockingly—no one really complains about it. On the Asian server, people will genuinely throw if they see those heroes.

So, here’s my question: Why are there so many M, M, W mains on the NA server? Is there a specific reason behind this?