When you mount things on wood (plywood over concrete/brick/block/etc. or into studs):
- You can remove and replace easily. If you want to replace in the exact same spot, use a slightly larger screw than the original and it will be very secure. If you want to replace in a different location, no problem at all.
- You can add things in multiple places, such as right next to another cabinet, with very little working space needed.
- You can often drive the screws in without any pilot holes. If you do want to have pilot holes, you can drill them straight through the cabinet (or other item) so there are no alignment issues.
When you mount things directly on concrete/brick/block/etc., you lose all those advantages. If you mount wood to the wall first, which does not normally need particular alignment and is easier than mounting cabinets (because it is a thin sheet rather than a big box) you bring back all of the advantages of mounting things into wood, and in fact have more flexibility than with a drywall over studs (which is why plywood is often the solution for mounting TVs on drywall over stud walls).
This is the usual solution not only for cabinets but also for:
- Circuit Breaker Panels and related equipment
- Computer networking, telephone and similar equipment
An extra step, but once it is done the rest is much easier.
As discussed in comments, and hinted at in the original post, for some things 3/4" may not be quite enough and you can double up 3/4" to get 1-1/2", which will let you use long enough screws to hold just about anything safely.
