Have you ever pulled a strut? Placing the chassis on jackstands and using a floor jack to support the control arm is about as dumb as crawling under the a car that is only supported by a floor jack, not jackstands. Sheez!!!

If you place the jackstands under the control arms, the weight of the car will keep the springs compressed, and it is safe to pull the struts. If the jackstands are properly placed the only thing that's going to knock the car off the stands and pop the springs is a magnitude 8.0+ earthquake if you're within a few miles of the epicenter.

If you really are safety conscious, you need to think about the advice you give real hard. It is VERY ill-advised!

If the control arm needs to be dropped to remove a spring, then then you place jackstands under the chassis and use the jack to lower the control arm and it should be safety chained to limit its vertical movement if the jack slips or slids out. Jack have rollers because they need to move due to the arc of the lifting arm, but for this reason they can also slide out from under the control arm due to the lateral force as it drops down.

Duke