It means for this year's record-breaking 23-race campaign, Mercedes has had to fall into line with the other nine teams.
Looking ahead to this season via a video on Mercedes' Youtube channel, Allison said: "It sadly means that we say goodbye to an old friend from 2020 which was the DAS system.
"It's a shame for us because that was a useful thing on our car, it brought us good performance in many tracks last year.
"So it's with a little bit of sadness that we say goodbye to it, but that's the rules and we go into 2021 with a conventional steering system like everybody else."
An area of concern for Mercedes going into the new season is the updated range of Pirelli tyres based on limited testing from last year.
For the coming campaign, downforce has been cut on the 2021 cars to help Pirelli manage the increasing loads on its tyres that had not altered in the past two seasons.
Pirelli has made changes to its rubber, but only on the back of three 30-minute runs in practice sessions in Portimão, Bahrain and Abu Dhabi.
"That's not really very much opportunity to take on board a new tyre and get ready for a new season with it because these tyres will affect the way that the car performs and they affect the way that you have to design the aerodynamic platform and the way that you have to set up the car," added Allison.
"So it's been a big challenge for us to try and stretch out that testing data that we had at the tracks last year and to try and make as much as we can out of the tyre data supplied to us by Pirelli so that we would be ready to really optimise the car around the characteristics of these new tyres.
"New tyres that are designed to help us race safely and fast all the way through the 2021 season."
GPFans is a multi-platform, multi-language brand dedicated to Formula One coverage. We bring you all the ins and outs of the sport, 24/7, everything from up-to-the-minute news and features to the latest viral stories and clips.
We believe that a new generation of exciting, outspoken drivers will make F1 more popular than ever before, and we want to give our users access to as much of their heroes as possible, on and off the track. From Lewis Hamilton to Max Verstappen, Daniel Ricciardo to Sebastian Vettel, we provide in-depth analysis of every every Grand Prix in the season, from Australia to Abu Dhabi.
With Formula One under the new ownership of Liberty Media, how the sport is being covered is evolving, and GPFans will look to be at the heart of this progression into new media, as one of the fastest-growing sites covering the king of motorsports.