Adventure in the context of "Adventure Bike" implies some level of offroad capability.
Why? I don't think it does.
For the sake of continuing this discussion let's say it does. As far as I know there are only a few bikes marketed as adventure bikes. Marketed as such as in the manufacturer calls it adventure, or adventure touring. The bikes have longer suspension travel and ground clearance, with aftermarket, or options making up the rest of the necessities to be more capable off pavement.
BMW and their GS. All models of which have varying levels of dirt worthiness.
KTM and the Adventure. Dirt worthiness, check.
Yamaha and the Super Tenere is listed as an adventure tourer on their website. As dirt worthy as the larger GS's.
None of the other bikes make claims to be adventure anything. All of that was done by journalists who thought they looked like adventure style bikes, or by riders who said, hey I can ride this thing off road and it does OK.
Now that said, you seem to be confusing adventure bikes and smaller dual sports. You haven't really addressed those that tell you you are wrong. You have zero experience in riding any of the bikes on your list on road or off (well none that you've mentioned). Your only experience on dirt is your 250 and only once.
You started by spouting off an opinion from an article of things you've heard. I will tell you personally that I will ride my F800GS places (and at speeds) where I would not ride a regular street bike. Is it a true trail bike? No it isn't. Does anyone I know actually think it is, no.
I am still not really sure what you are trying to get from this. Are you or are you not interested in adventure bikes? What is it you are trying to say? That adventure bikes are not dirtbikes? Yeah everyone knows. That's why they call them something else. Are many of them suited to light off roading, yes they are. Are many of them suited to more aggressive off road riding? Yes with some modifications and a skilled rider.