You can have as many alt-accounts as you want, as long as you don't use it to deceive,spam,scam or send unsolicited messages.
Scenario:
Ben will just post in Off Topic Section Only
And if "Ben" is only posting in the off-topic section, he shouldn't be here.
It wont matter unless you spam or post crap, i have seen high ranked members that post mostly on off-topic. You can even scam, it wont matter since you dont get banned in this forum for scamming, so you can do whatever you want but dont spam
The difference is that you are linking your accounts up. If you post regularly on one account its somewhat okay but if you farm accounts solely on the intention of selling it, it would be bad. Especially if you are contributing nothing to the community at all.