Possibly, but as I recall it from many years ago, they focussed on what they claimed would be the greater capacity of the roads converted from railways, while looking only, or mostly, at buses in motion along them. They didn't consider the effect of vehicles stopping at intermediate stations. They also did not consider the costs and the disruption of the conversions themselves.
I remember one example (from fifty years ago) involving Paddington. Today, there are far more trains and we've just spent vast sums electrifying the lines. My guess is that anyone who whispered into a minister's ear that we should abandon all that investment and put passengers through several years of disruption while spending further vast sums on an unproved idea might be told where to go.
Or take the example of Waterloo. Britain's busiest rail terminal. Tens of thousands of passengers every day travelling to Conservative-held constituencies in Surrey, Hampshire, etc. (Or, in the interests of political balance, possibly even more passengers travelling to Labour constituencies in the Greater London area and beyond.) The work that would be needed to convert it to a coach terminal would make the disruption of the part-closure in August 2017 seem like heaven, and would go on for years!