Rails' FormBuilder acts as a proxy, handing developers a toolbox for rendering forms. But complex forms often lead to inconsistent structure, param drift, and error handling confusion.

The Template Method pattern, used by ActionForm with Phlex, shifts control. Instead of yielding tools, it defines a rendering algorithm with named steps. Developers override specific parts without rewriting the whole process.

This approach unifies UI structure and data contracts. Elements declare both input attributes and output types, making params derivation automatic. Conditional rendering, error display, and nesting become structured phases, not repeated rituals.

Expect better maintainability in complex domains. The trade-off? Simpler CRUD forms may not need this level of formalization. The question remains: are you building forms or an assembly line?