Is efficiency the only advantage of switching regulators over LDOs?
The primary reason for selecting a switching regulator is efficiency; but at high current/power levels, size and cooling becomes an issue for linear regulators.
Let’s compare an example of using a switcher versus a linear regulator to produce a 3.3V output at 3A from a 12V input. The linear regulator will dissipate a lot of power with a 3A load, Pd = (12V-3.3V) x 3A = 26.1W. This will require a large, finned heatsink to dissipate the heat, probably around 6” x 6” x 1” which is too large to be mounted on a PCB.
In contrast, a switching regulator with 90% efficiency at a 3A load will dissipate, Pd = (3.3V x 3A)/(1-0.9) = ~1W which may be cooled by the surrounding PCB copper or just a small heatsink. So the tradeoff between switchers and linear regulators is really efficiency and size.
Also, linear regulators are generally cheaper and easier to implement.