Those blockers should be things that give you falsifiable stories, no?
So if someone says "it's because we're blocked on [slow delivery of designs from another team]" and you measure that specifically, and then improve it, and you notice the team's output hasn't changed, you've learned something.
I've certainly seen those reasons before, but haven't seen people turn them into specifically measured things versus "ok let's see if we can improve it" with often little or ineffective followup.
So if someone says "it's because we're blocked on [slow delivery of designs from another team]" and you measure that specifically, and then improve it, and you notice the team's output hasn't changed, you've learned something.
I've certainly seen those reasons before, but haven't seen people turn them into specifically measured things versus "ok let's see if we can improve it" with often little or ineffective followup.