> I think people should be encouraged to think of all cryptocurrencies as scams.
You are encouraging people to "think" something that you personally know not to be true.
IOW, you are not encouraging them to "think" anything. You are just feeding them a conclusion, and you are spreading a lie.
You might believe that is a white lie, but it's a lie nonetheless. Worse still, it's the type of lie that, if repeated often enough, damages all the reputation from honest people and destroys all chance of good work coming from the space. The lie becomes a self-fulfilling prophecy.
You can do better than that. I am not telling you to do a 180 in your opinion, or to support any crypto project in particular. But at the very least, stop feeding people with the conclusion and actually state the principles behind your reasoning.
Heuristics and "rules of thumb" help when there is uncertainty and when there is risk associated with a decision, but before applying an heuristic you can and should remove as much uncertainty as possible.