I'm also having the very same issue. I don't think it's a matter of having the same computer. For whatever reason, when launching Logic for the very first time, about a year and a half ago, I remember not needing to enable software monitoring. I could hear myself using my macbook's built in mic and a pair of external headphones. Recording was good and playback was solid.
Then I remember relaunching my Logic session and panicking over not being able to hear myself. I remember eventually finding out about software monitoring but it's less than ideal. Now, I can hear myself fairly well since I've been using an audio interface to plug in, but the volume of the signal doesn't match its strength on the dbFS indicator. I need to add slapback delay just to hear myself when recording vocal takes.
I can't even adjust delay to taste. I have to rely on it for my vocal to cut through AND sit in the mix.