(Spoilers Main) Another point Team Blackfyre could have used in their favour
Apart from Daemon Blackfyre being sexy with washboard abs, being legitimized by his father, owning the Targaryen sword Blackfyre (a symbol of legitimacy), Daeron II's questionable legitimacy through rumours, lords being disgruntled by increasing dornish influence and pro-dornish policies, etc, Team Blackfyre could have also used the fact that the last dragon died when Daeron II was born - blaming him for the death of dragons. The smallfolk (and some lords) are a superstitious bunch and would easily lap up this anti-daeron propaganda. Do you think they would have done that?