I'm not so sure. At my last company, we sold to four reasonably separate industries with a small amount of overlap. The four lines of products had nothing in common to look at - different shapes and styles, different colours. The marketing department liked the different colours because it made sorting the propaganda cough sorry, I mean 'info packs' easier. But the effect was that there was no commonality in the field - a user from one industry crossing into another would not recognise our equipment.
For the marketing power of unified forms and colour schemes, see Apple. Colour schemes all by themselves probably aren't enough, but they are a fundamental part of 'form'.
I don't think you can use Apple to make this point. Apple do not have a company colour and they just have one very simple logo: an apple (not a weird union of A, P, L & E). Software gets logos usually in the form of an icon. Hardware has iconic photography. Icons and logos change with time. This is sophisticated adult branding.
For the marketing power of unified forms and colour schemes, see Apple. Colour schemes all by themselves probably aren't enough, but they are a fundamental part of 'form'.