By only supporting simple single property accesses. All that this can do is print values from an object — no loops, conditionals, filters, methods, or anything else — like the others support. Think string interpolation, not templates.
You should remove the need to wrap the replacement strings in {} so the templates don't need to be rewritten. As it stands now, you're requiring people to write a template once, than rewrite it, and then debug the final result. Better to just use basic HTML.
