i do think it helps, if half the population is still isolating, if people are only going out half as often or getting half as close, it's got to make a positive impact versus unrestrained spread.
this has always been about flattening the curve, slowing the rate of infection so that hospitals are not overwhelmed, and some continued spread of the virus is expected. We're learning the extent of isolation necessary, the precautions that are most effective, and also very importantly the shutdowns, even as we come out of them, have driven home to most people the severity of this and reinforced the importance of masks, hand washing etc - so that as we understand the most effective precautions, people are already prepared and willing to acknowledge the importance of following those precautions.
It's like a group project where 1/2 the people arent participating, but you still need to get an A or people will die. So even though there are still many ignorant and selfish fools out there still denying how important it is to be dilligent, there's enough people putting in effort that we can still get a B and limit the severity