His second point, "Double jQuery" is because of inconstancy in jQuery itself. For all event callbacks 'this' is the relevant DOM node, but for plugin functions

His second point, "Double jQuery" is because of inconstancy in jQuery itself. For all event callbacks 'this' is the relevant DOM node, but for plugin functions 'this' is a jQuery object. It is understandable that a plugin author would assume that it is a DOM node and since calling $(this) would just return itself they have no way of knowing. I wouldn't say it reflects on the plugin author at all.