Farrell will miss the Six Nations after opting to press pause on his international career, to protect his and his family’s mental health.
Bristol’s former Harlequins prop Sinckler helped England reach the World Cup semi-finals alongside Farrell, and praised the 32-year-old's decision.
London-born Sinckler also revealed he believes better pastoral care should be provided to top-level rugby stars.
“If I’m being honest, it’s only the beginning,” Sinckler told the BBC. “If you look at the workload players go through, especially the international players, guys have been in World Cup camp for five months, get a week’s rest and then come back playing week-in and week-out.
“I wouldn’t be surprised if more players did the same.
"It is a privilege to play for your country and it comes with a lot of responsibility, but I think the support system around that could be a lot better. As a player you kind of have to take the rough with the smooth.”
The Saracens rugby director criticised certain sections of the media, while at the World Cup Farrell had hit out at social media trolling.
“The same people that will be saying to you one minute that you are not doing so well, are the same people when it is going well who are singing your praises, so it comes part and parcel with the job,” said Sinckler.
“The main thing is having the support system in place because only the players who have been through it, and who are in it, actually understand the pressure that goes with performing.
“I don’t think it has anything to do with the fans, I just think the support for the players, in general, if I am being blunt and brutally honest, could be a lot better.”