"Tags" are often used to indicate problems. Some Wikipedia editors object to the practice of tagging instead of fixing, but there is value in pointing out an article's problems. Tagging allows editors to specialize, teaches editors and warns readers about subpar or problematic content. It is better if people solve the problems they encounter themselves, but not everyone may be able to. Editors are sometimes obliged to justify inclusion of tags, such as in the case of Template:POV.
Constructive criticism given in a civil, respectful manner is a vital part in a collaborative project like Wikipedia, and it should be welcomed rather than discouraged. Wikipedia values contributions from everyone—novices and experts alike. It is important to listen to readers who find an article biased, confusing or unconvincing. They might not have the expertise to fix those problems, but the fact that they report them probably means that an article needs improvement.