Mercy players do the opposite of what everybody else does. When mercy is overpowered/strong. They don't play her. When she is weak and off meta. They ONLY play her.

Numbers do not lie:

http://www.omnicmeta.com/p/pc-us-usage.html

These are the stats of mercy before her rework when she was weak/off meta. She saw a lot more play in lower SR. Nearly 2-3X more than any other support. The only SR where people played less mercy was in GM because they actually had the skills to play ana/zen effectively and yes even though ana had 1 of the lowest win rates back then. She was still slightly more viable than mercy.

http://www.omnicmeta.com/2018/01/overwatch-hero-meta-report-pc-jan-17.html

Fast forward to mercy in her prime. Notice the shift in usage rate? Mercy became overpowered and mandatory but all the lower SR players stopped playing her. While all the high SR players took advantage of mercy and played her a lot more because of how useful she was.

Mercy players did not get tired of mercy. They got tired of being constantly "told to play her"

When mercy is not viable in the meta again... all the mercy mains will go back to mercy. Nobody would be hounding them to play mercy and zen/ana/lucio/moira would not be too overpowered where you NEED ONE every game.

Don't worry. I guarantee you that will happen. History will repeat itself.

You obviously should NEVER be tell people who they can or can't play but come-on... you shocked that people want you to play the strongest heroes in competitive who also happen to be the hero most support players have been playing well before the rework? Like no joke. At 4000+ SR. People look at all your seasons and they go into your stats to see average stats for that hero. More than 70%+ of the mercy players i played with in my competitive games has been maining or 1 tricking mercy before her rework when she was just a non viable hero. Mercy has been popular since season 4. She has had the highest player base of any singular hero since season 4 and has had the highest MAIN rate since season 4. She didn't become viable until season 6.