It was impossible because previous to Vasily's work the paragraph above the listed guidelines would have read differently
What's more interesting? Ranulf inventing a spell to give animal intelligence to fires, something any magi with enough InVi could have done (nothing exceptionnal here), or Ranulf becoming the guy that brought to the order the way to imbue fires with intelligence?
Ranulf is an NPC. What's more fun for the actual players when they come up with an idea for a fun spell that's pretty clearly within the abilities of the arts but doesn't match one of the printed guidelines.
A I figure out an appropriate guideline and let them go.
B I tell them "No, you have to spend character years in the lab playing with a different rules subsystem and risking your character's health from botches (unless they abuse the lab safety rules in covenants) to do what the descriptions tell you that you should already be able to do."
I started a thread a while back asking if the spell chapter would be improved by a statement along the lines of he guidelines are examples not exhaustive and the responses I got answers from folks mostly said that this was obvious and not needed. suplemental spell guidlines
For exemple, your selective WomS spell could very well, for me, be such a result from experimentation. This is what researchers do! Pushing the boundaries of hermetic magic through daring experiments
But this doesn't have anything to do with taking the guidelines as exhaustive. Unusual results as a result of experimentation or a warping score in the lab is there regardless of how restrictive you think the spell guidelines should be.