They rely on others to help them. It’s a different question if you cannot proceed because you are absolutely dependent on others. In that case an email should be fine and you should continue working on something else.
If that’s a problem, you either have a bad plan and/or worklist.
I'm an employee in a large organisation, I rely on other people doing their job to get my job done and they rely on feedback to know what to prioritise. I can't just work on something else because I have schedules & deadlines, and clients don't care that something is late because the expert at database replication checked their email at 5:30pm, after I had to leave.
I feel like if your opinion has the caveat that it only works in orgs where it’s possible to skill up in everything then it’s probably only applicable to very small operations.