But private reserves are only useful for private people. Companies need their own reserve, where their reserves are under governance by the members and the directors. This means that they are much more valuable to business partners.

Those company reserves are also more valuable to the owners of the company, when combined, than separated into a private wallet for each person, because they can be used to increase the amount of business conducted at an above-linear rate.

So,
Betty has 2 Bitcoin.
John has 3 Bitcoin.
Frank has 5 Bitcoin.
Sally has ¾ Bitcoin.

They each put ½ Bitcoin into their company reserve (or the company earns that amount, in their names, and they don't pull that money out). That company now has 2 Bitcoin, and they each own ¼ of it, but they jointly control it.

If they try to close a business deal with a different company (rent equipment, hire an employee, contract a supplier, etc.) the other company will say, but are you solvent?
Yes. Our company has 2 Bitcoin in reserve. No problem. We got cash.

But this 2 Bitcoin is now at risk for loss, so they are compensated for accepting that risk with any profits the company collects. 

 yep, equity :)