The following two sentences use the indirect pronoun 'le' before the verb. Why is 'le' necessary in these cases? Is it considered incorrect if it's removed? Examples with and without 'le' are below.
1. Tú les das vino a mis abuelos.
2. Ella le muestra un sombrero nuevo al hombre.
I've heard native speakers omitting 'le' in similar sentence constructions, but I'm unsure if it's correct to do so or not.
1. Tú das vino a mis abuelos.
2. Ella muestra un sombrero nuevo al hombre.