Wikipedia cannot be considered as a reliable source mainly because this is a website that can be edited by anyone. There are some people who are very petty and would edit information because they hate certain people or because they would like to spread false rumors about people or the events that have taken place.
Wikipedia may sometimes be incorrect or there are not enough details that can support the claims of the page. A lot of the information that is written in Wikipedia come from secondary sources wherein you would need primary information coming from primary sources in order to consider the information that you will get as credible.