The phase function found in the DTE (not a filter) could be viewed as a 'reality enhancer', at least that's how I see it.
Usually, the more complex the phase the better* the texture can look close-up.*
(nature is amazingly complex and chaotic)

It mixes up the noise by adding more noise as turbulence and acts as a displacement device also.
(*Better? > maybe better, you can add too much phase and kill a texture too. A lot of phase will take longer to render also)

Phase can also control noise placement/turbulence even when 'Nothing' is selected as type.
Phase displaces (moves) the design, or patterns, in the texture noise you selected and enhances certain characteristics depending on the type.
You can use a totally different Phase type than what you're using for noise.
(Voroni Noise with Fractal Phase for example)
When you mess with the phase, you're actually making a displacement map (tells the noise areas how to move) where the noise you used will be modified.

A good example is to use Phase >Displaced Max with a sand/rock texture.
This makes a copy of the texture noise, then 'moves' the noise by a small amount, and then lightens any areas where the noise and copy overlap.
This is excellento for creating veeeery real stone/mountain textures. ; )
Kind of like a high contrast/offset displacement filter with auto level in Photoshop. Try it!
Ok?