So you get notified you have a few new voicemails and you need to take time checking them, and presumably robocalls leave robo-voicemail, and now each robocall ended up costing you more time than they would if you just hung up?
Both my VM providers transcribe voice mail into text. Glancing at a transcript to identify spam takes a second. More important I am not interrupted by calls and could check them at the time most convenient to me.
(If robocallers don’t leave voicemail...why?)