Just as the title says. I think at one point I had a random dream that this was a feature and was convinced it was until I checked. Basically, this would allow us to play with the 3 versions of Symmetra, the old beta Bastion, the old Torb that could build his turrets to level 3, the old barrier health ratio, etc. I don’t know about you, but I remember most of the old versions of heroes and they were sometimes really fun to just play around with. Specifically, the old lock-on-target Symmetra beam.
As a game developer myself I am aware that this could be difficult to add from a technical standpoint, as some of the fundamentals of the game’s code and how heroes interact may have changed as the years went on, so I don’t think anyone would expect these to be very stable.