I am not denying that it can be more efficient to distribute multiple serial runs if the problem is small enough, see for instance: How to achieve parallel running on FEniCS like parallel command in Matlab?
However, if the problem is large, there is gain in using multiple processors, see for instance figure 12 in that paper. Do you think the scaling in that figure is far of? The exact phrasing in the paper is:
Figure 12 presents strong scaling results for the steam turbine with over 36 M thermal and over 108 M displacement degrees-of-freedom (linear and quadratic elements).
The runtimes are good, and the scaling satisfactory, as observed for the turbocharger.