DO use audacity for:
mixing and mastering music
editing music
recording things for music (such as vocals)
DO NOT use audacity for:
making music from scratch
Oh god no Id never use Audacity even for mixing or mastering. Applying any effects to tracks in Audacity are applied
directly into the file. You can't tweak anything after the fact, you'd have to CTRL Z it. Full fledged DAWs use FX systems that allow you to tweak EQ and other effects and VST's at any time. It's overlayed, instead of applied. Makes it easier to EQ as well since you can have live previews/loops of your edits.