Why does nobody play Bastion in Deathmatch?

I’m new to Overwatch, currently at around 2200 SR and level 32. I always lose 1v1s, hardly ever win a single round. Yet I can pretty much always get top 4 in free-for-all and POTG using Bastion and yet I hardly ever see anybody using it. Why? IMO Bastion is very overpowered in deathmatch and I’m surprised nobody picks him. I just went 20-6 with him on Hollywood. I thought he would only be good in Chateau but turns out he’s good everywhere.

Bastion’s main strength is his turret mode, and for that to be truly effective, he needs some form of shields, protection. He’s just too slow and cumbersome for DM, running around solo and his self heal is almost no help in a 1v1 situation.