These laptops intended to be sold off store shelves try and hit a price point and grab attention at the same time .... so it might have a decent CPU or set of memory but then they need to cut price to appear a bargain. The mix of decent components with a couple of "cheap" ones usually has the cheap choices bottlenecking the system resulting in the quality and performance of the quality components being hampered by the low performance ones.
One of the more common money saving tactics is a 5400 rpm hard drive, which you see on the GE70