I'm a musician. For me, a great deal of the pleasure of being a musician is making fairly sophisticated, coherent music, with other musicians, in front of an audience.
Scales are not strictly necessary, but are part of an apparatus of making music work in the way that I enjoy it. They are a technology.
You're more than welcome to. If you try to discover what intervals between these random frequencies tend to be pleasing, or displeasing, you'll rediscover some of the intervals and scales covered above
You may enjoy looking up micro-tones. Where western scales are made up of whole-tones and semi-tones, other cultures don't necessarily use the 12 semi-tone based scale system. Notably, Toxic by Britany Spears samples some Bollywood music, where the backing singing uses a bit of micro-tonality. You can often find different satisfying intervals, although they won't necessarily have the same cultural context/baggage associated with the sounds and therefore won't convey the same strong connotations that a diminished chord might.
Musician here—strictly speaking, music itself isn't necessary. Armed with that knowledge, you should produce any combinations of sounds that please you.
Scales and Chords are broadly speaking just a way of neatly-ish categorizing sounds and moods. This is true of both most classical music and jazz, for example, but Jazz in particular has a very practical relationship with scales.
One of the personality tests of an improviser is how you think about the music - do you think vertically (in the chord), horizontally (in the mode), for example.
Most composers were musicians before that and a lot of instruments adhere to scales such as fretted instruments or percussive instruments like the piano.
Using scales gives people a familiar territory in which to compose music and a western audience will already be culturally attuned to those sensibilities.
