Turning off the site wide setting "enableajax", or indeed setting the user field "ajax" to false, appears to have almost zero impact on the use of ajax throughout the site.

Having these options is great, if they actually do something, however they are deeply misleading in what they offer to do.

Based on a simple scan of the code, there appears to only be 8 actual uses of the ajaxlib.php function ajaxenabled()--ignoring superficial uses found in testajaxlib.php

Almost all code that uses ajax assumes, without checking, that ajax is enabled. Even in code that has clearly had significant effort put in to provide a non-ajax fallback (like the file picker), the fallback version is only available through completely disabling javascript in the browser and allowing it to revert to using the contents of noscript tags. A similar situation is evident when attempting to select manual course enrolments in the enrol/users.php page, to give just two examples.

The prevailing suggestion seems to be to disable javascript in the browser (see Tim Hunt's comment http://moodle.org/mod/forum/discuss.php?d=170228#p746731) but then why do these settings exist?