Shape shifting clothing

[Berengar]

@Darki

And finally, near the end of that section (p.115), it is stated that spells can have both Technique and Form requisites, and multiple of each, on top of that. No restriction is given, other than rules to increase the spell's magnitude based on requisites. So yes, you can do whacky random stuff as long as you're willing to pay the price in magnitudes.

The book is littered with examples. And while of course those examples have been reviewed before their inclusion into the book, I see no reason to consider them special cases, having rules that tell you how it's done. Of course, using those rules would require agreement with your troupe... like everything else you do in the game.

So what am I missing?

You 'miss' deliberately, that the troupe, when deciding to "do whacky random stuff", modifies, redefines or leaves behind the game world of ArM5, Mythic Europe.

I had asked you in Card & Board Games ARCHIVE & LINKS to "spell out completely what your argument shall show", which you didn't.
Your post consists in a series of quotes from rules, how to compute the level of spells with requisites, and how to cast such spells. But it does not result in an argument, which spells are possible for Hermetic magi in 1220, or even, which spells should be possible IYC. Yes, we may 'infer', that the examples given in ArM5 p.114 Requisites should be safe, but that's all.
ArM5 to a degree needs to separate the game world - Mythic Europe - from the hard and fast game rules. ArM5 p.114 Requisites is the latter, and very carefully avoids statements about which guidelines a campaign should combine in a single spell or effect. I reckon that you have seen that by now.

Cheers