Spoken like somebody who has very little experience with horses.

Horses are highly social and highly tactile creatures. A trained domestic horse who is socialized to humans (but not imprinted) is generally quite happy to be ridden and we do our best not to cause harm.

That said, I wouldn't gently scold a horse that had grabbed somebody's arm and wouldn't let go, that warrants a smack and retraining. "She's always doing that" isn't acceptable. Respecting their decisions doesn't mean letting them be rude or dangerous.