But do you want to dive with people you don't trust? Obviously nothing is black and white. I'm just trying to understand the thoughts others have on the topic. Not a right or wrong issue for me; just more of a research question.
Sometimes a dive boat or dive charter won't let you go solo. Sometimes you don't know how the people going to act until you get in the water with them. You can talk dive plans until you're blue in the face and everybody nodded agreement...until you hit the water and next thing you know people doing stupid stuff like crawling into nooks and cranies that neither you nor them wanted to plan for. Or wanting to descend down to 140-ft on an 72-cuft tank because they saw a cool stingray.
It's very simple. You have the buddies that you have, either the ones that you have executed dozens or hundreds of dives with or they're insta-buddies. They could be fresh from OW, or have a few dozen dives under their belts, or hundreds of dives under their belts. Everybody is suppose to agree to a dive plan that's workable. When people begin to deviate from that plan, what are you going to do if you were to signal them and they won't repair from the deviation? Everybody has to make their own choices as far as their own safeties are concerned.
I personally wouldn't just take off, at least not without letting my buddy know that I'm heading up. But if my buddy were to drop like a rock down to 150-ft while our plan called for 80-ft, AND refused to even to look back at me? Sayonara. I'm staying where I'm at and either continue on solo or terminate the dive and go back to the boat.
There are lines that I will not cross. If I have 800-psi left and we're suppose to ascend but the person kept on swimming or descending heedless of my concerns? I'm outta here. If I KNOW for a fact that we're going out toward the open blue water and the buddy refuses to acknowledge my hand signals? I'm going back, good luck swimming to China. If the buddy thinks that it's cool to squeeze himself into a little opening? I'm not going in there. Descending down to 150-ft while we planned for 100-ft? Have fun by yourself because I'm not going.
I'm sure that there are lines where others wouldn't cross either. However, the points are that a) you should plan your dive and dive your plan, b) what are you going to do when people are deviating from the dive plan?