Some web pages are impossible to navigate without a pointing device. For example, it is possible for a client-side script (Javascript) to record the location of a click, and sent that back to the server as a new request. A server-side script then interprets the click position, corelate it to regions of a bitmap, then compute how to generate the reply HTML document.
Such a web page is completely inaccessible by a visually impaired user or any user who can only use a keyboard.
Other web pages that are inaccessible to keyboard-only users include ones that utilize Javascript to implement drop-down menus, or a floating frame that includes links. Such pages require (mouse) pointer events to display certain options or hyperlinks.