Thats old technology now. Timberjack built them about 10 years ago, long before the John Deere buyout. They were built purely as concept machines, not for true forestry use.
thing is unless you have to get somewhere or have to do a job that needs less ground disturbance than a Regular harvester you would spend all day just getting from where you parked the thing to the job site, then you have to walk from tree to tree. It would cost more money because you would have less output than a regular harvester.