Why does no one want to play tank?

Hello! This is a post from a "flex" player but usually plays tank 90% of games. Can anyone tell me why in this game nobody likes to play tank? In s0 I was gm2 peak both on my main and on my smurf and during my climb I noticed that people would always instalock dps or healer no matter what. What makes the vanguard role so unfun/undesirable to play in the current state of the game? Is it because that every vanguard are situational depending on your team comp and the only one that's viable in most situations is Strange so people are tired from playing him? I hope there are stats for overall pickrate because I literally see no one wanting to play this role without being a one trick/flex playe/being forced to. Thanks for listening to my rant!