People keep referencing the Pens 2016 team as an example of "depth". That team's top line was a rookie Sheary, Crosby and Hornqvist. The second line was Malkin, an aging Kunitz and a rookie Rust. That allowed them to run Kessel, Bonino, Hagelin on the 3rd line.
If the Pens did what the Oilers do and put Crosby, Malkin and Kessel all on one line, their depth isn't any better than what the Oilers have remaining with McDryman all on one line.
If people are going to crow about the Oilers duo of McDavid and Draisaitl being so much better than Crosby/Malkin, then surely they can still be productive with guys like Foegele, Kane, Hyman, Perry, etc. on their flanks so that they can spread their talent to 3 or 4 lines. Because that's what Crosby/Malkin did, and that's why they could have Kessel on the third line running his own line.