Multitools have variety of uses in the field that even excelent knife can't duplicate.

Saw: cutting wood without risking of breaking your knife

Pliers: if rope for tighting not available maybe there is some wire that can be used, also lifitng hot things of the fire, field repairs, tweezers

Scisors: personal hygene, medical work

Can opener: does better job than the knife in a safer manner

File: fine tunning traps, guns

Screwedrivers: small hole punchers, field repairs to striping down something

Nice big knife is a life saver but multi tool can sort of match its capabilities yet exceed them with extra tools. Plus if your blade breaks you are out of luck. If blade breaks on multitool there is always a second one to fall back on.