After a few games, I would say exactly the contrary.
I found very difficult to have trade boarder agreements, especially if you dont have a navy that explore oceans and get contacts with Asians/Americans civs. And when you have only one economic partner, Im not sure the benefits are enough sufficient.
When playing Rome by trying a domination Victory (I failed the Historical one), I had mercantilism and nationhood , which was a good combination for stability (and my worst enemy was collapsing risks), as well as expanding frontiers with great artists or producing tribunals (engineers) for poor cities. I only had Mali for vassal/economic partner (not a very good one), all the other civs didnt rely one me (I finally managed to get open borders with Babylonians... and they declared war one just one turn after!)
And if you build the Sistine, with many cities the benefits is huge (but I missed it in my play).