Anybody can edit WIKI entries in most instances. However, some categories are closely watched and monitored by mainstream agents and dupes.  Thus you may find your edits removed in short order.  I found that to be the case when I edited their information about oleander and finally got tired of the tug of war of having the information posted and removed over and over.

A couple of years ago a guy at Cal-Berkley came up with a program to trace the WIKI edits and found that many of the edits traced back to government agencies and pharma companies and such.  With billions of dollars in profits at stakes you can bet that the big corporations and their government servants pretty well pull all stops out - including editing and monitoring sites like WIKI and public forums, paid posters and trolls, etc.