The Orchestra is "non-trivial..." You have to hear "and feel" the oboes? The bassoons? The percussion, the strings? (violins 1st and 2nd, violas, cellos and bases) The horns? Trumpets, trombones... The Tubas?
And you need for it to breath, and swell... And get quiet?
The orchestra is its own thing... People who've never done it, or tried, don't appreciate the complexity associated with Orchestral accompaniment? And then it all has to "sit" So it's not like drums, bass, guitar, and vocals... Not at all :-) It's its own thang ;-) And when you hear it done well? You can "really" appreciate what goes in to it... There are so many moving parts? You have to respect the orchestra... It takes time, and again, it has to breath? Things get louder and softer, things are closer and farther away, things come in and out? The orchestra is non-trivial...