Magical Coherency Limit

Particle size limit past which dimensional linkage information along with most magical effects breaks down. This has consequences in practically every aspect of magic:
-Magic-based circuitry's transistors cannot go below 10μm, so conventional hard light circuitry is hard capped at a size 2000x larger than silicon. No carrying around smartphones etc ever with the given tech tree unless someone figures out infinite dimensional superimposition.
-Dramatically reduced effects of mundane disease. Loose (as in, not part of a larger organism) bacteria (typically under 5μm size) lack coherent souls/claims, so they have a really hard time affecting things with souls (i.e. humans).
-There are magical materials created by grinding magical materials with different alignments into very fine dust, then mixing them to get a bunch of 'in between'-aligned elemental material. Binder's Resin is an example of this.
-Arcane magic projections have a minimum edge thickness of ~10μm (30μm is 'sharp knife' territory, obsidian can get several orders of magnitude thinner). No creating infinitesimally thin planes to shear through things with basically no force required.