Yep... I feel old knowing about `<form action="/newsletter" method="post">` and handling form url encoded data server side

Indeed, don't you just copy and paste from Mailchimp?

"Hard" is the wrong term. But I'm certainly not alone in being rusty on this stuff. Uncontrolled components, form actions, imperatively reading all the <input> values, `x-www-form-urlencoded` data, etc. If you use this stuff on a daily basis, then I'm sorry for your suffering. I haven't touched it since 2015.