The 31-year-old supermodel lost contracts with H&M, Burberry and Chanel after photos of her allegedly snorting cocaine in a London music studio were published in the Daily Mirror tabloid last month.
In a statement, Moss has said she is addressing her problems and takes "full responsibility" for her actions.
British newspapers reported last week that she had checked into The Meadows clinic outside Phoenix.
"As for Kate Moss, I understand that she has apologized and is changing her life and I think that that is the most important thing," Stone said Tuesday.
"Whether or not a (fashion) house stands with her, or not, through it says more about the house than it does about her because someone who doesn't allow someone to fail, to grow, that would say a lot about them if they left her," the 47-year-old actress said.
"I think it is really terrific that someone makes a mistake, takes responsibility for it and deals with it," said the "Basic Instinct" star.
"Growing up, from being a child or young girl in the public eye, is a tremendously difficult, painful procedure so I don't think it is that dramatic of a deal to fail, to make a mistake, fix your life and go on in public."
Stone spoke at a press conference announcing that she is the new face of a Christian Dior skin-care line.