It literally styles itself as an encyclopedia, not a collection of summaries by "mainstream secondary sources".

https://en.wikipedia.org/wiki/Wikipedia:Five_pillars

> Wikipedia combines many features of general and specialized encyclopedias, almanacs, and gazetteers. Wikipedia is not a soapbox, an advertising platform, a social network, a vanity press, an experiment in anarchy or democracy, an indiscriminate collection of information, nor a web directory. It is not a dictionary, a newspaper, an instruction manual, nor a collection of source documents or media files, although some of its fellow Wikimedia projects are.