Originally, TS said that alts were allowed as long as they weren't online at the same time and didn't give the main account an unfair advantage. That was back when you could have garden plots or herb plots, but not both. Now every user can have access to both, has the position changed?
Furthermore, if you are a high enough level and have all the skills, fully expanded house and access to all resources there, how can having an alt give you an 'unfair' advantage?