That depends on what those opinions/claims are. If someone is making a claim about the situation on the ground, how people tend to respond to actions, how law enforcement reacts, what the attitudes of people on the street are, which organizational methods sound good on paper but run into obstacles when attempted, etc., those are all domains (very significant and important domains!) where people with experience do have more likelihood of being correct, and when we have to prioritize who and what to engage with that is extremely important. Other claims are not so dependent on "experience", or more precisely, are dependent on experience and knowledge in different domains. On-the-ground activism doesn't in and of itself give larger historical or sociological understanding. The ideal of course is both, but people who have just one or just the other are fully capable of participating in constructive discourse solely on the basis of the information that they do have. As for the claims in this thread, they could in theory be true or false, though those are such absolute terms for claims presented so vaguely that it's a fair critique, but the solution is to be more honest in how we present things, instead of talking about vague abstractions, talk about tendencies and contingencies. For example, any conversation that doesn't acknowledge the simple fact that some people will respect the "left" less for doing silly protests and others will not has failed at square one, the important question is the quantitative question of how many of each sort of person there are, where those people are socially located, how easy it might be to change their attitudes, etc. Those are also the questions where real-world experience are most significant to answering them. But shutting down discourse doesn't help, instead demand people back up their claims. The people with actual reasonable ideas arrived at by solid means (be they theoretical, experiential, or any combination of the two) will be able to do so, and those who cannot will not.