They usually are designed to produce neighborhoods where no one ever needs to spend any time searching for a free parking space— which leads to a great deal of suffering for anyone not in an automobile, since such neighborhoods have vast expanses of surface parking that are completely inhospitable to human beings, and are very difficult to serve with public transit.
They also often require an amenity that is very expensive to produce (parking spaces, especially structured spaces) be provided for free, which incentivizes people to own cars and drive everywhere— exactly what we don't want in urban areas, since cars pollute a lot, are dangerous, and require huge amounts of scarce land to store and transport.
But that problem is still a luxury problem. It's not some fundamental right for people to own a car. If you want luxury benefits, you should have to pay luxury pricing. I'm not saying you shouldn't have the right to own a car, just that, like any luxury good, it shouldn't be cheap.
In Seattle there are many public transportation options. Sure, it could be much better, but it's still available and quite feasible to use.
The problem, and the reason why parking requirements exist, is because people externalize that "suffering" on others. They decide they need a car anyway, and then they park that car on other streets, or they park overnight illegally on private property, etc.
It's not like parking requirement laws fell from the sky one day on a bunch of stone tablets. They didn't exist a hundred years ago, but were created and became ubiquitous across the U.S. as cars became more popular because there were such problems when parking is in short supply.
Now, maybe there are some alternative solutions -- maybe you could get people to sign some sort of blood oath that they'll never own a car while living at a particular address, or maybe we could pass laws that prohibit cars from being registered to addresses that lack parking...? (Maybe we could require that in order to register a car, you have to prove you have the right to a place to park it, and stop treating parking as a public good?) But until there's some better solution, the underlying problem that parking requirements were created to solve still exists.
People are very, very good at sharing their suffering with everyone else and society is typically worse off for it. It takes a lot of work to prevent that from happening.