Actually, I'd like to read the article about the
play without finding
out the ending. Is that an unreasonable thing to ask?
Reading the article as it appeared on 26 July 2010,  there is an
entire section called "Identity of the murderer"... If I did not want
to learn the identity of the murderer, I would have skipped over this
section.* That's what I did for years before I became an editor. If I
suspected a section would contain spoilers, I skipped it. When looking
up books I plan to read, I still do this.
That's one of the reasons for sections - they can allow readers to
quickly find just the info they are looking for. I can look up Harry
Potter and the Deathly Hallows , and if I didn't want a spoiler but
wanted to read about pricing problems, there is a section in the Table
of Contents, right at the top, called "Price wars and other
controversies". This allows me to bypass the "Synopsis" section,
including the subsections "Plot introduction" and "Plot summary".
Perhaps this is not the way everyone reads, but I think context clues
can give their own warning to the reader.
I'm also not sure if there are any articles out there that have
spoilers under a section you might not expect them to be. For example,
I wouldn't expect to find a spoiler under the "Release date" section.
But I also can't think of a good reason why it would be there anyways,
and it should probably be moved to the plot section(s).
Just my two cents. :)
*A quick glance did not show this information to be listed in any
other section, however I did not read the whole article word for word