Comment by dredmorbius

Adding to this: a chief advantage of antibiotics (particularly the early ones) is that they were both broad-spectrum (controlling a vast array of bacteria) and sparing of non-bacterial cells (e.g., those of our own bodies).

Evolved resistance is changing at least the first part of that relationship.

Phages as you note are far more tailored, and may (if I understand correctly) need to be targeted to a patient's specific infection's genetic line. It's as if you had to select ammunition based on the specific type of target you were hunting, if not specific individuals. In the early days of antibiotics it was far more a case of "fire and forget" with a single magic bullet. (Not literally always, but for the overwhelming majority of bacterial infections.)