It’s important if you want to write portable programs. As you may know, the Intel Fortran compilers can’t be used on all hardware: Intel Fortran on Snapdragon chips
Imagine being a handyman and buying an expensive set of wrenches. But when you come to the job, the bolts don’t fit. Either you’ll need to buy/borrow a different set of wrenches, or use a different set of bolts. In both cases it will cause extra costs or delays.