The policy pretty much everywhere that I have encountered, since I was in elementary school in the 1980s, has been that tertiary sources like encyclopedias should never be cited for the information they contain (except when you are citing it because the point of interest isn't the information that is in the encyclopedia but the fact that it is in the encyclopedia, such as if you are writing about how certain events are presented in various venues.) I think the first elementary school research paper I did was an exception and permitted citing one encyclopedia among the three sources required.

Tertiary sources have always been, in most venues, "acceptable" only as research tools to find primary and secondary sources,

(Oddly, though, its become common in the last few years for even reputable news media sources to cite Wikipedia as an authoritative source. I don't see that really as progress in Wikipedia's acceptance so much as a sign of the increasing laxity of standards in journalism.)