Suppose that suddenly, out of nowhere, a longest-chain appears that reorgs the last 15 blocks. Such an attack could be accomplished from time-to-time even by a minority attacker who is either lucky or pays heavily for extra temporary hashrate. Depending on how clever the attacker is, this can be quite lucrative. It's feasible, especially if Coinbase or Binance was victimized, that an unofficial edict could go out use invalidateblock. After a short period of moderate confusion, nodes would have agreed to reject this fork, temporarily suspending Nakamoto Consensus, and Bitcoin would proceed as before, and the attacker, who spent perhaps millions of dollars executing this attack, would be chastised and impoverished, chilling the ambitions of other attackers who would attempt a similar caper.
My questions: why would we think that such a community reorg wouldn't happen? Second, why not just have this coded into the software? If a node suddenly sees a new block appear at height 10 below the latest height the node has seen, this gets automatically invalidated. What goes wrong?