This is especially important for brand new labels. The industry is now flooded with so many labels, that to establish yourself properly and get yourself noticed you need to employ a certain level of consistency in the music you release.
This is the surest way of building a loyal fanbase who will hopefully come back every time you release a record. That's not to say you have to put out half a dozen carbon-copies of the first record in the same year, but establishing yourself with a certain sound, or within a particular niche gives you an identity, which can be invaluable. Even established labels that release varied music have some consistent thread running through their catalogue, so for labels breaking into the market it's an absolute must.