If in most uses minds, "www.example.com" is the same as "example.com", then "example.com" is less confusing because they have probably never heard of the word "subdomain".
Perhaps they should be taught.
Otherwise let's move on to making nuclear reactors less confusing.
Developers and techies are users too and they're much less likely to call tech support in general.
This harms them far more than it helps the people who need help.