For one-off actions, like the "save" and "cancel" buttons, callbacks don't descend into madness. Most UIs have very few commands which need true event handling.

For one-off actions, like the "save" and "cancel" buttons, callbacks don't descend into madness. Most UIs have very few commands which need true event handling. And the ones that do, the commands are often pretty simple one-button -> one-command. Sometimes many-buttons -> parameterized-command. For everything else, you can use data-binding. If you're already writing lexically scoped render functions, you can trivially create a data-bindable local object in a variable to eliminate the event management process. Instead of an onclick event for a checkbox, you can trivially set the checked property to be equal to an observable value box containing a boolean. With the right abstractions, callback spaghetti is not an issue.