Food is primary seen in coil as of 2.3 turn 6-9. Alot of raid leaders are really demanding that you buy food and use it to help out the raid.I seldom see people using food, even in Ex fights they haven't beaten yet.
Ex primals have low ilvl requirements on the other hand so food is not mandatory and honestly ex primals even titan ex are puggable. So its not strange you haven't seen much food use.