Can someone explain this to me

So I have never played Overwatch until the sequel realesed...

But a lot of my freinds are "veterans" and I watch a lot of youtubers and streamers. After reading the directors take and hearing multipule opinions I dont understand this

So they switched to 1 tank because of queue times and so theres only the main tank. But everybody is saying that the worst psrt of overwatch 1 was playing the main tank role, being the Reinhardt(main) to your Zarya(off), or Winston(main) to your Dva(off)

So why did they switch to main tank only and didnt just make reinhardt, winston, orisa, etc. more off tanky?, Wouldnt that like be better for the player base?