No matter what anybody says dude soil IS important. I used to try to grow in little cups with no drainage and just use ground dirt and always had skinny stalks that fell over like you described . No matter what lights I used, even in this grow I'm doing now I just used regular cheap bag dirt with no pearlite and had weak stalks. I left these plants in cups for like 2 months and they barely grew, when I moved them the roots were just coming through the dirt.

I've grown in in heavy pearlite and good soil and had them get root bound in two weeks in the same cups. With HUGE stalks. I KNOW dirt can be a problem, the other things contribute too. You need good lights AND good soil. I've tried and failed enough and researched enough to know that much.