[astrobe_]

Transitivity is not an issue: "obéir à ses instincts" and "suivre ces instincts".

So "s'incrire à" is not incorrect per se, e.g. "s'inscrire à des cours de danse". Even, you must say "s'inscrire à la mairie" (e.g. for poll lists) and not "s'inscrire dans la mairie".

I think that what is technically correct is to use "à" when you talk about where you sign in or register (usually a one-time action) and "dans" when you talk about signing in to perform a recurring activity.

That little à word derives from the Latin words "ab" and "ad", which you can find in words ("adjacent", "adverb", "addition", "adventure"... hemmm I mean *aventure"; sometimes English is more Latin than French) which tell the idea of proximity or direction.