I know what you mean about people seeming to think they can make up rules that they think are rules. I can't stand all that yellow fluoro clothing most cyclists seem to think is obligatory. I had a bus driver telling me I was supposed to wear it the other day, at about 7:45 am in Victoria. I'm on a really High Viz bike, really good lights on, reflector bits all over it, and on my shoes, and he's telling me I should be wearing 'reflctory stuff' up high because 'that's where I'm looking' according to him. Like you can only see on a plane at 5ft off the ground ... what?
I ride with lights on almost all the time. Certainly on grey days like this - basically only when I want to charge my phone do I not. Why would you not? But then, that's because I don't wear the flouro clothing, and I tend to be using dynamos more often than not.