In my case, I've discovered that Devonthink (document/notes management app) is responsible. I've been meaning to file a bug report about it.
I'm surprised that Apple's power management doesn't have an alert for this. Surely an app that causes my Mac to become glowing hot while sitting in my backpack, not to mention slowly running out of battery, is a pretty important thing to intercept. Meanwhile, I keep being asked if Chrome should be allowed to find devices on my network, which doesn't seem nearly as important.
In Linux, KDE's power manager PowerDevil shows if something is blocking device or display sleep for example. I don't think it's hard to add an indicator in macOS, too.
Another option might be another section for apps preventing sleep, like power hungry applications.
An indicator and selective overrides is the way, IMHO. Invisible if you don't look, but it's there when you need it.
so, like a white picket fence vs an invisible fence™ for your dog: white picket fence (not to mention two kids) is so unsightly people would never use it as a metaphor for bliss, why not just give the dog his unexpected-can't-see-it-coming-shock collar? let him discover through repeated trial and error what he's allowed and what he is not.
sounds about right, you've help me articulate what I don't like about modern so-called design