You don't even need to go back that far, look at Halo 5. People complaining that it doesn't feel like Halo anymore. Gears stayed true to the series and people complain that it feels too much like Gears.
I feel like you meant to say Halo 4. Cause Halo 5 brought back a lot of the "Halo" stuff that Halo 4 removed. Halo 5 may have new mechanics but it still feels like Halo.