An index hint is a bug report about the optimiser

Forcing an index makes one query faster today and freezes a decision that the optimiser would otherwise revisit as the data changes.

SELECT * FROM orders FORCE INDEX (idx_placed)
WHERE placed_at > ? AND state = 'paid';

-- why it was needed: the optimiser chose idx_state, which
-- is 90% 'paid' and therefore useless.

-- the actual fix, which removes the hint:
ANALYZE TABLE orders UPDATE HISTOGRAM ON state;

-- a histogram tells the optimiser about the skew, which
-- is the information it was missing.

A hint is appropriate as a temporary measure with a comment and a ticket, and permanent hints accumulate into a schema nobody can change — dropping an index becomes impossible because six queries name it. Histogram statistics cover most of the cases where a hint seemed necessary and need regenerating after a large data change.