There are a couple of reasons to "touch the web.config" file. One is to restart the website Application Pool and the other is to force changes to other configuration files, like the user.config, to be read.
The ASP.NET runtime monitors the Web.config file to detect when you make changes, but it does not monitor the user.config file. So whenever you make a change in user.config you need to edit Web.config to make it pick up your changes in user.config. The easiest way to do this is to open the web.config, add a line to the bottom of it and then save the file. IIS will detect the change, restart the application which in turn reads the user.config.