Because the shelf and service lives on them suck compared to a lithium or alkaline, zincs are pure 1960s tech. Once upon a time, they were the only ones that could manage devices that had a high initial load relative to the basic load IIRC, but that was 20, 30 years ago. Modern alkalines can and will take zincs to the woodshed every day, in any role.

For brands, I find duracell, rayovac (AVOID the red/blue ones, those suck, get the silver/black ones) and energizer work best for alkalines, duracell or surefire if it is lithiums.