Imagine there was a message so important that you show it at the top of the page, on every page on the whole site, and in every language; no matter if you are logged in or not, and no matter how many times you have seen it before.

Then imagine all you ever hear about these messages is a passing mention elsewhere,

The survey, which ran in a central sitenotice in October and November of last year ... and whether they donated to the Wikimedia Foundation (or not).

Of course they did not donate. They never saw any fundrasing, nor Wikimaina notices, so nobody ever encounters such users either.

In http://thread.gmane.org/gmane.science.linguistics.wikipedia.technical/42824 Aryeh Gregor Simetrical+wikilist@gmail.com writes:

My understanding is that we use JS for this so that a) search engines don't pick up the notices (which are typically transient),

That is throwing the baby out with the bathwater. Also search engines request that you don't try to present different content to them than regular users. I'm sure site notices would not spoil search engine results.

b) we avoid Squid cache, so they can be visible immediately.

I.e., they are of the utmost importance that everybody see.

Please use a different technical solution. Site notices and ways to just see them once etc. have been around at least since UNIX. Never before has one used a method that excludes users of certain devices from ever knowing about them.

Isn't an accessible web site a pre-requisite for some grant monies? At least provide site messages that gracefully degrade if one does not use fancy browsers, but not disappear completely!