You could just do an introductory adventure that's not fatal. But extreme stress is a bonding moment for many players.
In-so-far as the OP, meatgrinders specifically do have a disadvantage over an introductory adventure if they're the model "reroll a new character when the previous one dies, only one character at a time". The party you end up may have only been together for the very tail end of the meatgrinders session(s).
A character funnel version, or the all guardsmen party version, doesn't have that. Character funnels each player controls multiple characters, and some number survive to the end. The all guardsmen model didn't kill all the characters ... a number were incapacitated due to wounds and evacuated. The resulting group was put together from the evacuees.