Elements of type 'Receivers' are not supported at the 'Site' scope. This feature could not be installed.

from my old documentation for Sharepoint 2007


While working on installing event receiver as feature receive error
 "Elements of type 'Receivers' are not supported at the 'Site' scope.  This feature could not be installed. "

This is because receivers scope limited to web site.

See here more details from Microsoft documentation