Dan McLaughlin gets this right, and at least in my neck of the woods, it applies at the state and local levels, as well as the federal levels:
… tabloid news coverage, yellow journalism and unscrupulous personal attacks were a standard feature of national politics in the early decades of the American Republic. But instant-publishing technology removes even minimal restraints on pernicious gossip or baseless attacks. Anyone with a social media following can start a raging online mob without the slightest bit of reflection.
That’s why people with dignity and a decent respect for their families steer clear of elective office, leaving only people like Trump and the Clintons — people incapable of shame and hermetically removed from the life of ordinary human beings. Trump and Clinton have proved that the best defense against a career-ending scandal, failure or offense is to have too many of them for anyone to count.
Another difference, beyond “instant-publishing technology,” is the huge scope of government roles. Even at the local level, running for government gives one authority over a wide range of people’s issues, and with government labor unions, anybody who might not negotiate with kid gloves is instantly a target of organized and very hostile groups.
I imagine this dynamic on the small level grows to the big one. Even if national politics has always been a viper pit, local politics may have been more tolerable. So, people might have gotten a taste for true public service at the local level, thus fortifying them for moves up the ladder. Nowadays, that pipeline is drying up.