my understanding from an English professor is less about its reliability of information, but more its reliability regarding citing sources. you can't cite something that consistently changes
The schools should have used wikipedia as an opportunity to teach media literacy. You don't use wiki as your source, you go to the cited sources and investigate those. Use the cited sources a in your school reports.
That might be one reason why some warned against using it, but I definitely had teachers in middle school and high school that explicitly said not to use it because it could be changed by anyone including people who could be wrong or lying.
And the ability for folks to change it and provide inaccurate sources. It's peer reviewed for the most part and academia wants officially peer reviewed sources.
It's also just often completely inaccurate. The standards it uses to cite works make them pretty much useless: any good information on Wikipedia is on there by accident.
That is wildly inaccurate and you know it. There are like 6.5 million articles on Wikipedia and the majority (since people are pedantic, we'll say 50.1%) are well cited and accurate