Turnkey,
That plastic was recommened and used by a number of people in years past. I can't say I'm a fan of that though. Never really was. If you have reasonably dry foundation or one with the few occasional damp spots, it probably doesn't hurt anything and could help. But I've seen people Drylok their walls and create another problem in one instance.
Virtually all CMU walls with parging on the exterior and applied waterproofing, get some dents and dings during backfill which damages the membrane in hopefully small areas. Additionally, most waterproofing applications are light IMO. Spray applications should be double coated. Hand applied once is enough when done right. What allot of people with perfectly dry walls in their basements don't realize is that some moisture will make it's way to the CMU (block). So long as it's limited in quantity and has a way to exit the block, your going to have apparently dry walls. Reason being, the limited moisture uptake of the CMU (they are nearly sponges) makes it's way to the interior and then is evaporated into the basement area. If it's limited it never appears wet. Have you ever noticed a seemingly perfectly dry basement in the summertime that seems to get a little extra close with humidity? More than the other areas of the house and often more than the outside humidity at any given time. That's because it doesn't have the nice dry winter inside air to transfer too and the air already starts out a little more humid. That moisture is coming from the slab and the walls, but predominately from the seemingly dry walls, assuming there is plastic under the slab.
Applying plastic or Drylok effectively puts a membrane there and traps the moisture in the wall cavity or behind the plastic. Not generally a problem with the Drylok as that moisture would have to collect over time, make it's way to the bottom of the wall (below the grade of the concrete slab), and not have an exit path, in order to create any problems. The plastic can actually trap the moisture behind the sheathing on wetter basements, where it collects and runs down the wall. It exists onto the basement floor lacking any other avenue of dispersal. Often you don't see this occur during construction, but I have. Seen it occur over time on a few occasions.
A friend of mine Dryloked their entire basement a year ago and then called me to trace a wet spot that appeared a few months later near one corner. I told them what I suspected was going on; the the moisture in the wall could not find it's way to the sub-slab CMU blockwork and was exiting the wall about one course up, running down the face of the wall and then onto the floor. It was trapped in one cell that somehow got filled during construction, getting saturated, then puddling in that cell, and even the Drylok couldn't hold it out.
I don't write this to make anyone who has used either of these methods wary. I generally have a favorable view of Drylok. Rather, it's to give an understanding or what occurs when you use interior side vapor or moisture barriers, of any type, on a foundation wall that is below outside grade. Knowing that, I always recommend the airspace along the wall. Drylok or not it's advisable. Moving air gets replenished and transports moisture. A little moisture can become allot over time if it can't exit.
HTH