You gotta be kiddin' right? You don't think they opened cement bags before the invention of the one hand knife? Most EO Jack's can be opened one handed, sheaths put blades right where you can always access them a good leather sheath can have a clip and protect a well made tool at the same time adding years to its life. Hell you can beat a bag of cement open with a rock and they're all around places where you'd likely open a bag of cement. Why are you so hostile?
Buy what you like, use what you buy but don't forget slip joints have been around doin' the same jobs most modern knives today do, I personally think they look better doin' it and show a higher degree of craftsmanship in the process. Look at some of the old large folding hunters, many had locking blades any had 4" blades. Lastly it all comes down to preference and most use a combination of both old school and modern in their daily lives, that's why people come here and stay because we like knives.
With 2000 post in 2 years you're a part of the community, you may have come lookin' for an answer but you stayed.