I agree although the issue is whether or not age is disqualifying. I don’t think there was a particular reason voters wanted Biden’s age. He had raised his profile as a part of the Obama white house and then leveraged that into the popularity to win a primary and later the general election. It just so happens that he was already in his 70s by the end of Obama’s second term and also didn’t run in 2016. In another universe where he ended up being Al Gore’s vice president from 2000 to 2008 and ran for president in 2008 or 2012, he wouldn’t have had any less appeal to voters than he did in 2020.
It’s not a matter of voters deliberately picking 70+ year olds, it’s that voters are aware of the risks and vote for the candidates anyway. Then the risks materialize into reality. Being the president is an incredibly high pressure job. The guys who get elected in their 50s and 60s don’t look the same by the end of it. It’s also a job where you might need to get woken up in the middle of the night and make a decision that could change the fate of the world and you always need to be ready to make that decision.
It’s rightly a scandal that Biden (and by my guess Trump) was in mental decline by the end of his first term and apparently tried to conceal the extent of it in his reelection bid. It should’ve been an issue in the primaries. But voters have goldfish brains on this and a whole host of other issues and blame everyone but themselves.