Thanks for the explanation and links, Bob & Antoine (P)! I have simply overlooked the fact that block validation is more than the act of validation of the block itself, but it also includes the updating of the state: UTXO set, etc. It’s not surprise that this is an issue that came up often during the history of bitcoin (I was not aware of the details). It’s a fun fact that Gregory Maxwell’s verification flag proposal was exactly 10 years old yesterday!