Bugzilla allows passing product/components/keywords URL parameters (like https://bugzilla.mozilla.org/enter_bug.cgi?product=Firefox ) to make user reporters automatically set the correct project when creating a task.
These URLs with parameters are put on feedback wikipages and other prominent places to tell people where to file technical issues.
Being able to have the project field pre-filled decreases work for triagers and developers as they often wouldn't have to manually add the correct project(s) to newly created tickets.
T3320 already implemented numerous parameters; unfortunately not a "project(s)" one. T1906 (finding a list of available projects) is also related here.