In addition to the arguments listed there the thing that bothered me most about it was that it imposed a straitjacket on the editorializing of any article that contained spoilers, you now had to bend over backwards to partition it into spoiler and non-spoiler sections.
I still think though that they should do a better separation between the actual information and the story elements though.
Also, who should spoiler warnings in an article about a TV series benefit? People who haven't seen the latest series? People who haven't seen it at all?
Should the summary say nothing about how Walt turns to crime (which wasn't apparent to me when I started watching it), and instead describe Breaking Bad in vague terms as the struggles of a New Mexico man to provide for his family?
Spoiler warnings are inherently at odds with writing a succinct and accurate summary of a given subject, which is what Wikipedia strives to do.
Other commenters here are right, if you don't want something spoiled for you then simply don't read encyclopedia articles about it.
You wanted some information about the structure of the aired episodes, there's plenty of TV-guide like sources for that that aren't encyclopedias.
I, like the author, am very sensitive to spoilers and completely agree that people for whom spoilers ruin the enjoyment of a work should still be able to reap the benefits of an encyclopedia for the work's "metadata" -- information about the cast, running time, season and episode count, production, etc. However, the article, ironically and much to my horror (Edit: actually the author has a warning at the top of the page, which I missed), spoils the end of Breaking Bad, one of television's most popular shows, a show that is/was still on my to watch list.
But indirectly, this functionality could exist in a Javascript widget/gadget/script that users who do not wish to see spoilers can install themselves, into their registered account's settings. The installation process is usually very simple, a small copy/paste into a configuration file.
I think that no direct modifications to articles to accommodate the script would be allowed; this includes special templates, <!-- hidden comments-->, or even the existing benign {{anchor}} template (usually used to mark HTML URL#link targets), if it's used to mark text {{anchor|spoiler}} for the script.
So the script has to be smart and dependent only the article text itself. It could selectively activate on articles in any category containing the words Television or Film, on sections named Plot or Synopsis, and simply collapse (autohide), or redact (blackout) any paragraphs which contain proper names, or keywords present in a list (die, dead, death, kill, wed, wedd*, marry, married, etc.)
A good starting point would be the text selection and redaction functionality as shown in the ProseSize.js script, which also presents a "Page size" link in the left navigation bar and, when clicked, instantly styles all the eligible article text background in yellow. Our widget could just use black.
I leave it to Javascript and CSS wizards to go further.
Wikipedia is already dying a slow and painful agony and has been for a while, no need to accelerate it by adding more trivia and irrelevant features to it.
