The 99.9% figure refers to the default 43-byte limit in Bitcoin Knots policy. The remaining ~0.01% was mostly related to a pattern used by the now-defunct Samourai Wallet. According to Luke Dashjr, that case was largely the result of lazy coding and could have been optimized to fit within 43 bytes anyway. Even 83 bytes is already more than sufficient, and as far as I’m aware no normal monetary transactions exceed that size. Future “smart contracts” should first exist and prove their value in the wild before we start loosening or dismantling node policy for hypothetical use cases that may never materialize. Engineering discipline means solving real problems, not pre-optimizing the protocol for ghosts.