in Idea 6.0 is the following, especially the bold part, correct? It seems so unlikely.
Assuming that Tomcat is not installed locally, adding a configuration in "Run/Debug Configurations" for Tomcat/Remote will not show anything suitable in the "Application Server" dropdown. In that case, "configure" has to be used to add a local Tomcat, which has to be installed just to satisfy that dialog (which is being opened using "configure" in "Run/Debug Configurations"). After closing that dialog Tomcat can be uninstalled. (It does not matter that the resulting Tomcat configuration is invalid; that results in a warning only and remote debugging works. Only when there is no application server chosen at all, rather than a broken one, debugging is impossible because all corresponding menu items and buttons are grey and the key combinations have no effect then.)