I have a Strategy & Tactics board game simulation of Anzio. It has an accurate map, and the the actual forces duplicated in battalions and regimental size.
The allies are in a low land area facing the Alban Hills between the beachhead and Rome.
As the article states, it is obvious by looking at the map that what was needed was a fast penetration into the Alban Hills on D-Day or thereafter.
I don’t think they wanted to risk it because of the bad experience at Salerno. But doing that might have made the invasion succeed quickly.
Fortunately Hitler wanted to smash the invasion without a realistic understanding of the situation, the local commanders wanted to attack differently.
Yes, I have subscribed to S&T since USN was published. You ever hang out at Consimworld?