Why do you think it is generally accepted medical practice to get bedridden patients up and walking as soon as possible?

The longer you are bedridden, the more muscle tone and flexibility you lose. The sooner you get out of bed, the shorter your recovery time is. If the patient had joint surgery, getting up and moving ensure that they will be able to regain full or close to full range of motion in the joint. For general surgery, the risk of blood clots grows higher the longer the patient stays in bed.