>>54965387Two reasons. One is that because NPC's and wild pokemon are low level compared to the Gyms and Bosses so if you don't grind you'll likely be lower level than the Gyms and Bosses, however, as you showed Gyms and Elite 4
The other reason is that it because wild Pokemon are lower level, it takes more time to raise them up to level at of the rest of your team.
The level curve complaints are founded but its highly exaggerated.