THe rules do allow you to have more than one account and to sell your accounts.
Where did you read this? From one ip, you can only have 1 acc, or am I wrong?
You are allowed to have more than 1 account AFAIK (although, I don't). If you run a crypto business, for example, this could benefit you (having a personal + business account for example)
You aren't allowed to create another account after being banned to circumvent the ban (only if you're going into meta to ask why or to PM a mod to review). That's where you may be thinking the 1 account per IP applies.
To answer the question from OP, 1 and only ever 1. If I ever create a crypto-related business, I would probably create another to represent the business wholly, but otherwise it'll only ever be 1.
I also share the same thoughts like you. For example, I create one account first when I didn't know about the platform and wanted to understand how it works. Regarding to business accounts, I wish we had an actual 'business account' because it would enable us to differentiate.
Furthermore, I'm wondering how easy it is to grow a business account to a high rank because right now, I'm doing quiet well with my personal