We are not saying to use compressors at all; in fact, we are suggesting using compressors & automation together.

It is not uncommon to compress & automate the same track. Especially for a vocal track.

Sometimes there may be some parts that are too loud & too much compression can squash those parts.

Sometimes there may be some parts that are too quiet & it helps to brings those up using automation to make them more audible without having to overdrive your makeup gain.

Using too much compression can also cause the breathes to sound too loud, because the vocals are being squashed by the compressor, but then the compressor eases up on the breathes & suddenly the breathes sound louder than the vocal.

Automating the clip gain can sometimes work better than automating the volume, because the automation is happening before the signal reaches the compressor & that can result for a more consistent sound.