Absolutely wrong. I have many windows10 rigs with 2 or 4 gb and 6 to 13 gpu´s and i can mine without any problem. System Ram has nothing to do with the DAG!
I guess its dependant on software then. But the last software I used with Win10 was Claymore and that definately wouldn't of worked with 2 GB of ram. He designed the DAG so it would load the DAG directly onto the GPU without having to be stored on the hard drive or ram however it wouldn't load with less than 4GB of memory. Ubuntu didn't have this issue.
I haven't used the newer software like lolminer or phoenix with Win10, only under Ubuntu where I didn't get this issue. Either way. DDR3 is still very cheap. There are tons of people getting rid of 4GB sticks or less. Most motherboards usually have 4 slots for memory so you can even get away with using 4x 1gb. The biggest issue is sourcing a GPU these days.