civicrm_processProfile hook ignored
Turns out, this hook is not called when a profile form is submitted on the front-end of the site. The hook is fired during the creation/edit of a profile. Found through a Google search

Page Title: hook_civicrm_processProfile - CiviCRM 4.3 Documentation ARCHIVE ...
Page Link: wiki.civicrm.org:8090/confluence/pages/viewpage.action?pageId=86638695


Dropped the port 8090 in the SERP link to see the wiki page that says:


  This hook is invoked when processing a submitted CiviCRM profile form (e.g. for "civicrm/profile/create" or "civicrm/profile/edit"). This hook may be used to inject additional markup, scripts, or styles on the profile.


I dont know why that important detail was dropped among other important details. The most recent wiki has no such text.

Edit: added as issue in 2017devdocs.