It is indeed harmless. Unless somebody is silly enough to make their own decisions based on what some anonymous poster said. And as I noted before, if somebody does that, they can only blame themselves, not an anonymous poster (with some obviously unverified personal information).
A community can come here to potentially be exposed to stock/company information they otherwise hadn't seen. And maybe exchange opinions about the stock/company. But any rational investor would not make decisions based on comments by anonymous posters. They would do, and rely upon, their own DD, and credible sources where they can verify pertinent information. That is where the truth is about the stock/company.
I don't care about the "truth" regarding claimed personal trades, because those trades are not pertinent to making investment decisions. It doesn't matter. IMO.
If you do decide to trust an anonymous poster, my suggestion would be to VERIFY before you act. JMHO. But folks are free to act based on comments from an anonymous poster, if they wish. Just don't misdirect the blame towards the anonymous poster if it doesn't work out.
I realize with a stock like mvis, some folks might just be gambling, or playing around. So they might act based on a "tip" they received (maybe from an anonymous poster). But again, if that is the basis of their "investment", they can only blame themselves if that approaches fails.
All JMHO.