There are very specific rules on what constitutes “proper attribution” under Wikipedia’s rules, and it’s not saying “this came from Wikipedia” or providing a simple link. It’s providing the full license, which is going to be longer than pretty much anything anyone would want to quote.
As pointed out above, they are covered by copyright. And if someone wants to use them elsewhere they need to follow actual Fair Use provisions to a T (the 5% thing is bogus) or follow the license.
Link to the article, with an optional couple of sentences quoted. If people here care to read it all they can go read it. If you’re worried that the article will change in the meantime (a hint you shouldn’t be using it as a source in the first place) link to a specific version of the article (date and time).
Or, even better, link to the original source rather than the wikipedia article. I don’t care how much you protest, wikipedia articles just copy/paraphrase other sources, or outright make things up. That kind of destroys the “wkipedia copyright” argument right there.
I’m not a fan of using Wikipedia as a source in general, but that particular argument makes no sense. By that logic, the original sources are themselves just copying/paraphrasing other sources or making things up, so nothing could be copyrighted anywhere. That’s not how copyright laws work, and your understanding of Wikipedia sounds a little off too.
For completeness sake, there is one big exception to copyright when quoting: things like mathematical proofs, where you absolutely need to quote verbatim. Discussion here. However, it still will often be better to give a link where the original is online.