> Now why do I have to care about "cloning templates" every time I render some html template?

You do not have to. It's a self-sustained injury by the author. You can compile the templates once and just execute them.

The issue is that author wants to specify page titles in the main templates. If you pass titles as a context, you can split base.tmpl into BASE_BEGIN, BASE_END and use them in the final templates.

Yes, you will have to pass the title depending on the page template during the But his tactics will break anyway when you try to support different languages.