There is no absolute reason why AoA is necessary, it’s value is relative to the source of alternate data and information provided.
Arguing the reverse, in commercial aircraft AoA has piloting value at low speed, usually at values which should be avoided; however at other times it provides little information relative to structural or performance limits dependent on speed. For modern auto-controls, AoA provides better precision and reaction to the dominant flight control parameter.
Desperately trying to recall an aircraft without AoA; Comet, Dove, … Gnat - except the Bedford resident festooned with probes and vanes !