It doesn't make sense, because GPL means only GPL comes out, not only GPL can go in:

>Many of the most common free-software licenses, especially the permissive licenses, such as the original MIT/X license, BSD licenses (in the three-clause and two-clause forms, though not the original four-clause form), MPL 2.0, and LGPL, are GPL-compatible. That is, their code can be combined with a program under the GPL without conflict, and the new combination would have the GPL applied to the whole (but the other license would not so apply). https://en.wikipedia.org/wiki/License_compatibility#GPL_comp...

A model that contains no GPL code makes sense so that people using non-GPL licenses don't violate it.