The moment you ask anyone to switch, Hanzo or not, you’re looking at a pretty high chance of pissing anyone off.
No one likes being told directly what to do. Especially if they themselves don’t do that to other people.
Also Hanzo at your rank usually isn’t the only reason you’d lose a match, focusing on just that one hero is a pretty meme way to look at things instead of actually thinking about what each and every single hero on your team did and how they affected the match.
But I guess if you knew, you wouldn’t be in the same rank as that Hanzo.