It took my dog a lot longer to learn "NO!" than it did for him to understand the significance of praise and rewards, but he did learn it in the end. And I do emphatically think it is wrong to try and achieve training results just through positive reinforcement.
The trouble is that all the theorising and half-informed talk of dominance theory, pack mentality and so on just creates white noise that gets in the way of a perfectly humane commonsense approach.
Of course training should be squarely based on praise and reward but it is completely easy and kind to combine this with assertive owner-behaviours that let your dog see that he is behaving in an unwanted way. We even do this with our children, for goodness sake. Why wouldn't we do it with our dogs?
You don't have to dress these owner-behaviours up with silly ideas of dominance, and you certainly don't have to use them as an excuse for behaving in an intimidating way.
In one of your posts, OP, you mention not letting dogs barge through doors ahead of you, and I think this is an example of the kinds of situation in which the owner can set limits by using their body in a confident way. You can firmly and calmly put yourself between the dog and the door, displacing him from the position he wants to be in and requiring him to respect your occupancy of the space. I have done that a lot when my dog is over-excited at the front door when a visitor has knocked. I can see how it calms him. A switch goes in his brain and his whole body says "Oh, ok, I'm not the one who has to manage this situation".
And as well as using your body, I think it is fine to use your voice firmly to interrupt undesirable behaviours. I found it really hard to work out how to do this (perhaps because of all the focus on positive reinforcement) but eventually life takes over, and situations accumulate in which you instinctively adopt a sharp "NO!" (most often, for me, it has been when my dog starts rolling in fox poo
but of course it is also going to be whenever the dog starts doing something that is potentially dangerous for himself or others).
That isn't "dominance", etc. In some cases it mimics an instinctive parenting behaviour (keeping a young one safe), in others it just replicates the boundaries that all social social creatures routinely create and reinforce just so that they can get along together without constantly being hassled.
I have a PRT, and like many terriers these dogs adopt a slightly wary approach to the world: If humans behave towards them in an intimidating way they will very quickly learn that they are not to be trusted. So it has always been very necessary for me to understand the difference between being calmly assertive and being intimidating. It isn't hard to maintain that distinction in practice! I'm not trying to dominate him, just allowing him to see that there are some boundaries to his behaviour. And it is very evident how reassuring he finds those boundaries.