To be fair the french primaries were mainly run by the PS and the Republicans and the winner of these primaries were always going to be candidates from these two parties.
It was useful for Hollande in 2012 and it was useful for Fillon until he ruined it because it helps give you momentum and gives wider mediatic coverage to your program, now after what happened one can ask if it will still be there in 2022 but for the PS it at least was useful in the sense that it shows how big was the gap between the politics and the electors voting for them.
It could have been useful for Hamon even without Melenchon and Macron if he wasn't backstabbed by almost everyone, Aubry, Montebourg, Hamon and cie didn't do so in 2012 after Hollande won, and the argument that "Hamon was the first to betray the party" is fallacious at best considering it had next to zero impact in the end (and well you know...)
A few interesting tidbits from the last Harris poll
If we had to believe in polls, as it is Fillon is basically the most likely to be out, the main remaining point is the 38% of Hamon's electors (~3% of overall electors) still undecided and who they will go for (Hamon, Melenchon or Macron).
A shame we don't have data for Dupont Aignan electors though, as they're the only ones Fillon can most likely bring back to him.
