I wonder where you saw this. Whatever, I have not noticed any “companionship” issue, except that care must be taken to allow sufficient space between broad beans and onions as they are both growing strongly in spring. Say 45cm (18 inches).
Thanks for that. I can see shade being an issue and will consider this when spacing. Being able to put beans next to onions, two of my favourite crops, will help with getting the most from my half plot allotment