There have been some theories on this phenomenon, with the most prevalent being the tendency for Wikipedia pages to move up a “classification chain”. According to this theory, the Wikipedia Manual of Style guidelines on how to write the lead section of an article recommend that articles begin by defining the topic of the article. A consequence of this style is that the first sentence of an article is almost always a definitional statement, a direct answer to the question “what is [the subject]?”
Unfortunately they patched the mscz downloads and now they’re charging for merely viewing more than one page of certain scores. Musescore4 is great but I hope musescore.com burns.