No, it's not puzzling
I was puzzled about the tendency of globalist parties to put up incompetent candidates. Hillary, Corbyn, Hollande. Vastly better people were available. Why not use them?
Standing back from the noise, it's not odd at all. It's normal.
Before the current GENUINE split, all parties were identical and politics ran like clockwork. A party that was scheduled to lose this election would put up a useless placeholder. Either a senile old servant like Dole or an incompetent like McGovern who needed to be pushed out.
Things are GENUINELY different now, which means the expectations don't work well. Nevertheless, parties are still using the tactic because it had always worked before.
Dems expected to lose to identical globalist Jeb in 2016, so they ran senile old Hillary to avoid wasting new talent. Corbyn and Hollande fit the incompetent model. Hollande wasn't expected to win against Sarkozy, so the tactic failed.