Wikipedia is a live publishing platform. As such copyright and plagiarism issues are taken very seriously by the English Wikipedia community.
Except for brief quotations, copying content from copyrighted sources onto Wikipedia is against policy. Whether direct copying or close paraphrasing, plagiarism and copyright violation are disruptive and time-consuming for volunteers to clean up.
It can also result in real life implications for those involved such as academic demotion or expulsion at some universities, and users editing under their real names may leave behind a permanent Internet record of their plagiarism.