Indeed; there are others who buy MOT's stolen from testing stations, and up until recently have been able to obtain tax with them. As everything can be checked online now, such certificates are of little use. Consequently, from next year, you will just get a print out of the vehicle and testing station details, together with any failed items. Usefully, any advisories will also be on the same sheet, so can't be hidden by anyone selling the vehicle.
Chris