Some descriptions are definitely taken directly from Wikipedia with little to no changes. If anything, I'd argue that a plagiarism case can be made here.
Wikipedia is a free and accessible source of information. It was created for people to use open information
Although you are right, the general rule on the Internet mandates to mention the sources you took the information from. That's common knowledge. But, in case you don't know the specific rules of this forum, not doing it can lead to a ban due to plagiarism, as joniboini said before.