I'll give a little more context to my answer. For me it's more how I was trained in long range precision. For the Scout Sniper Basic Course, we shot the KD portion with the sand sock. It's best for teaching new shooters how to control the rifle in prone shooting. Once I went through the Urban Course, I completely dumped the sock for everything other than zeroing. Dynamic shooting requires rapid adjustments from supported standing/kneeling positions, and having 4-6 seconds of time from exposure to shot fired on 3D head targets really teaches you what you need and what you don't. Applying that back into the field, using hand only as rear support taught me how to stabilize the rifle without carrying additional gear. When I went through the Advanced Course, the only student still using the sand sock was one who had just graduated the basic course.
I've tried using rear monopods and while they work in some scenarios, I've found them to work in few situations where I shoot. Bench or belly on a hard pad or well packed Earth? Sure, they give good stability and as close to a full rest as you can get without one. Soft sandy ground? Constantly adjusting them from shot to shot causing me to be very slow in comparison to how I've shot in the past. Anything positional or dynamic? No thank you, it's just in my way.
I still don't carry a rear bag in the field but I do use one on static ranges when zeroing or going for tiny groups. I like my slings to attach just in front of the toe of the stock for me to grip instead and use my sweat rag or other gear I already have out to assist if I need a little more rise or am watching through the scope for extended durations of time. Data books work great for that!