Putting boots on does not mean you take good care of your horses legs - of course there is much more to it than that.
But putting boots on, protects your horses legs.
Of course there are suppliments - whether it be oral or IM Injections. Proper nutrition.
Proper warm up, proper conditioning, proper cooling off. *I don't mean hop on and start trotting like many do, or walk for 2 minutes then break into a trot*
Hosing legs, liniment legs, wrap legs.
There is far more to protection than just boots - but boots are up there for importance.