Calling it evil is absolutely a moral judgment. What I’m saying is, if the description tells you what behaviors the creature engages in that make it evil, then the fact that it’s evil should be self-evident. Like, if a monster entry says “these things eat babies,” I don’t really need an alignment system to tell me they’re evil. I can work that out for myself pretty easily.
I can see the convenience argument if the description doesn’t say why the monster is evil. It saves word count as well as reading for the DM, so while if isn’t my preference, I can see where one who does prefer that approach might be coming from. But if the description does say why they’re evil, as I would prefer, I don’t see how labeling them evil makes any difference.
But at a certain point you're going to describe behaviors that most people do consider evil. No description is ever going to be entirely objective, all descriptions that indicate meaningful things about behavior are going to be subjective. Is causing pain and suffering in others rewarding for you?
For the vast, vast majority of people that play D&D it would be considered evil. D&D is not an advanced philosophy course for people to plumb the depths of what morality means, it's a game. One that uses oversimplification and glosses over details constantly. As always if you don't like alignment ignore it.