I briefly search 'than they would be if ...' on Google, but nothing interesting relevant shows up upon a glimpse. Here's an example sentence:
Proof-of-concept technologies, although important, are less valuable than they would be if they were supported by careful experiments that identify key attributes of the design or principles that span applications.
My understanding is it's saying that it's more valuable if they are supported by experiments. My understanding of using 'than' is that it compares two things, A bigger than B, etc; here a subsentence goes after than, instead of just a noun. Is this a special usage of than? What type of grammar or sentence structure is 'something than they would be ...' called?