Apart from emphasizing certain scenes/actions/lines etc., music can also do the complete opposite and de-emphasize. This might be needed especially when you have to help over bad acting, which might occur even in very professional productions.
Sometimes, reactions of actors or of the visual language might be excessively stated and might in certain situations even seem unintentionally funny. As composer, you can tone down these situations by scoring it in a calmer, more subtle way than you would actually do if you took the acting serious.
Also, just “scoring through” such moments without the music taking any particular notice or even scoring a hit point will help to make scenes “less important”.
Helping actors is probably the most frequent need for such a scoring approach but it can actually also help to shape the story arc. For instance unavoidable hints on a dramatic plot twist later in the movie that might raise suspicion with the audience can actively be de-emphasized with the music to divert the attention from it and make the plot twist later on more surprising.