OMG, I must be dead.
Certainly, there is always some risk stemming from whatever way a vehicle is supported.
I hope everyone agrees that there is way to much risk to get under a vehicle supported by only a jack.
I don't think you meant it that way but jack stands should not be a deterrent to DIY. That assumes that I did my homework on how to determine good locations for the stands. That also assumes the jack stand rating is well under the load and the jack is still in place just snugged to the vehicle as back up. . Depending on what I am doing, I use additional jack stands in different locations as another back up plan especially if I am removing significant weight from one corner. IMO the risk of using jack stands is too high if the base of the stand is not on a level surface, if there is a risk that a stand leg can sink into the surface or the vehicle is on an incline Even then there are ways to address those circumstances. I would rather not be alone when I am under a vehicle. When I remember I have my phone within reach. Our risk is reduced working under an X5. Mine is lowered and I can still shimmy underneath in most areas. Of course, that won't be beneficial when the tire is removed.
Educating technicians on the risks of using jacks and jack stands improperly when lifting vehicles