I always assumed that an ideal query planner would be in the best position to decide what plan is best based if it had real-time access to up-to-date data stati

I always assumed that an ideal query planner would be in the best position to decide what plan is best based if it had real-time access to up-to-date data statistics and available indexes. Adding hints might hinder performance improvements when migrating to a newer version of a database, as the newer version might have a better way to execute your query than what the hint is suggesting. You'd have to revisit all your hints when upgrading.