A compelling post. Something it doesn't mention that I immediately wonder about is how you ensure the decision to escalate from "a quick DM" to a "full business case review" (or whatever) isn't unreasonably biased.
If everyone is working with good intent then this doesn't matter. But the real world is full of unconscious 'isms so I suspect there's a risk that underrepresented folks are more likely to trip the extra process flag and thereby get slowed down disproportionately, leading to negative feedback loops.
Just don't make the gates so flexible that due diligence can be avoided
Yes and the word you want isn't "flexible" it's "proportional".
A gate is best when it's proportional to what goes through it. Small project? The business case is "Pam thinks it's could be a good idea". Large project? The business case is a formal study. The word "proportional" makes it much easier for all the participants to understand that the gate is a sliding scale.