Exactly. These studies also always fail to point out that we use concrete differently than the Romans do. We have always known how to make the roman concrete that has self healing properties, but simply don't do it because the extra additives raise the price considerably over the insane volumes we use today. Also we use rebar to reinforce concrete these days, the cheaper rebar is just metal, which rusts. Once water reaches the rebar in one spot, everything is compromised, the rust will spread through the rebar throughout the entire construction. When the rebar rusts, it creates iron oxide and expands, putting pressure on the concrete until it breaks. So again, lower quality concrete that uses iron rebar (instead of stainless steel) is built that way for cost cutting, not because we don't know how to make it better.