Installing block under garage walls is the best thing… or the worst thing, depending on who you ask.  Block has its place.  If the grade around the perimeter of the garage will be within 6” of wood siding or must be higher than the floor due to elevation change, then block is a necessity.  If your garage will not fall into the mentioned scenarios, my recommendation is “no block”.  Block has a few major downfalls.  It wicks salty water like a sponge which leads to degradation, it is not elastic, which means it will crack when the floor cracks (and it will), and it needs to be waterproofed.  Wood structures alone are very resilient to movement and the treated bottom plate are designed for ground contact for upwards of 40 years.