I agree with the list, except #7, the future will be what it will be and either they can see it or theycan't. Picking up on potentials or possibilities is not the same thing as predicting the future. If it changes from what they saw it just means they were picking up on potential energies or intentions rather than precognitively viewing the future.
And #8 is not even giving a reason why a reading could be inaccurate, but instead gives an example where it might be accurate but the person doesn't like what they heard.
I agree they could improve on these things a lot with more practice...and too many amateurs jump into giving readings because it is unregulated and for some can be easy money. But, even for the most skilled and experienced readers, I'm not sure how consistent they can be. Readings are such a nebulous, Neptunian thing. It's like asking why someone who throws darts while wearing a blindfold missed the target.
I think that both can be true, owing to skill level/gifts. If you accept that psychic-ness, for lack of a better word, is real, then there should be people who can definitively see the future. I think there are some. This would, to me, be an extremely gifted person who has honed their gifts over years.
I think there also can be people who read the potentials of energy or who understand, sense or feel motivations, and who use that information to then extrapolate an outcome. So to the extent that they don't necessarily see or feel an end result, but see or feel the way things are now, or possibly a potential trend, then their extrapolation could be incorrect.
I wish there was a better way to truly understand how a reader reads, what their gifts are and what they can realistically do with them, before paying for a reading. Some do a good job explaining this, others don't.