They weren't, but they were a hell of a lot stronger than Trump. And Biden for that matter.
The reality is there's clearly a double standard in how Americans - both male and female - view women as candidates. Look at how they attacked Kamala for having a monogamous relationship with Willie Brown while Trump cheated on 3 spouses and sexually assaulted somewhere between 1 and 25 people.
Does anyone think there's a chance that a woman who was caught cheating on her spouse could get elected? And it's not just sex stuff, the way opinions and mannerisms are scrutinized is different too. There's 100x as many ways for a woman to be cringe as a man.
In 2020 Trump's approval was so low that Bill Cosby could've beaten him.
Biden was a long-time failed presidential candidate even when he was younger and better at speaking. In the same primary election in 2008 where Obama was first and Hillary was second, Biden was a total embarrassment - if I recall he didn't get a single delegate. But in 2020 he rode the popularity of the Obama administration to the top just like Clinton did in 2016.
The tendency of democratic voters, especially in early primary states to pick some familiar name is completely devastating to Democrat electability. The last candidate to win on his own merits rather than being associated with someone else was Obama and he crushed it. Anyone associated with past administrations needs to be ruled out from the get go because they almost certainly suck.