Sorry but that solution is not a solution. When you get your main up to max, then your two alts are easier to level up. In this solution, you now have two mains. When you want to raid, you have to find a whole different group on another console instead of doing x3 on one. Etc etc.
Hopefully this works for you, but for me, it's bullshit.
Well, it isn't like this was a feature that Bungie talked about, said they were going to include, and ultimately failed to deliver on.
The reason it will work for me is that it is simply the only option.
Everyone's reasoning for wanting to play on multiple platforms can be different but for me it was to play with my son and friends on Xbox and also play on PC with the smoothest gameplay (60 FPS) and at the highest fidelity/settings with optional control devices (M&KB + Xbox One Elite controller).
I think it would be a bit of a rare case to find 6 people who play on both a console and PC simultaneously weekly if a cross-save was made available (I mean if so why wouldn't you just choose to play the best version of the game which will likely be the PC version?).
That said, I wish there were a cross-save option, but again, Bungie never suggested that there would be one.