One more thing. If we put a white list in the consensus, like minimally allowed monetary transactions. Then if some functionality needs to be added, lets say quantum resistant Bitcoin address fromat we will need to change the consensus. And changing the consensus is really hard part. That is why it uses minimal set of rules that all agree on them.

I understand the issue, I was now laying out a way of thinking about this,, i.e. what would be the guaranteed way to ban spam? Probably by allowing only P2WPKH outputs at the consensus level. Since that cannot be done, we need to think of other ways and in order to do so we need a theoretical framework first so that we can define what is a valid transaction in the first place. It seems to me that a valid tx can be defined as the one that transfer UTXO ownership in the most parsimonious way possible. This is however hard to translate into software requirements without banning all transactions that don't have a particular shape. Even if we banned OP_FALSE OP_IF at the consensus level there would still be other ways to embed arbitrary data, this is I believe the Cruz of the matter. Do you agree? And most importantly, are you a bot?