If someone asks for advice, or is paying you to coach them, then they're very likely to listen to your advice.
If you're not being paid, you could still say things like, "we should get greivous wounds. I think bot should get it because mid is single target"
Or "they have a lot of armor. I think that getting LW first will give more damage than finishing that zeal item."
Since you specifically used the phrase "calling them out", yeah, anything that could be considered "calling out" is to be avoided. You can give advice.
If you start out with something like "What are you (noobs) building?" or "Is this your first time?" Then your advice will generally not be listened to.
If you want to give advice, give advice. Once. "Bot should lane swap to top to take the tower" "Zhonya's could help against Zed"
All the tiptoeing around "can I ask you a question? Could I give you some advice?" comes off as insulting.