It got way easier since I started using Redux Forms (Only if you use redux though). Great library, super simple to use once you got used to it.

I don't use any useless frameworks and don't feel any pain.

I am handling form validation without writing a single line of JS and without learning something new by using HTML5 API like required, type="email" with the help of Bunny Validation - #1 World Form Validation library. Docs are a bit outdated, you can now init form validation by adding validator="bunny" to <form>. Later there will be support for multi-steps forms out of the box.

Why would it be a pain? Hooking onChange or onBlur or onSubmit, depending on the type of input, works like a charm, and covers whatever you need to validate. There's also some great UI component libraries available if you don't feel like writing your own.