I don't think the answer is necessarily to throw cash at multiple high end guys either, but I've lost a lot of confidence in the "spin gold out of straw," approach. It wasn't just Colome that tanked last season, and even though the pen stabilized a bit, it wasn't enough. History is slowly repeating itself.
I totally agree that having a solid 3-4 arms like you named would go a long way and make it possible to hide guys like Pagan & Thielbar, though if Canterino is now strictly a relief arm (not saying you're wrong) the SP pipeline is taking some early Ls. The Twins had success with the front heavy strategy in '19. Duffey, May, and Rogers all had career years and threw 50ish innings. People forget how meh the rest of that bullpen was (they DFA'd their closer at the deadline ffs.) Another issue that gets less attention, but has already been mentioned, is SPs going deeper into games. Even with a solid 3-4 arms, you can't have a rotation turning in short starts 2-3 times per turn.