Your points have merit.
It's true that a lot of the shortened appearances by starters are by design now.
But most teams still use a setup guy/conventional 9th inning closer approach rather than having a 'relief ace' who comes in whenever he's most needed.
We used Kimbrel as a conventional closer, and that's what he wanted to be and apparently still wants to be-the guy who gets the saves.
In the 2018 postseason we used Barnes, Kelly and Brasier as the setup guys or bridge to Kimbrel.