the accumulator delays cycling of the compressor, somewhat, until it has to be "paid back" later, and allows longer run-times of the compressor instead of short-cycling.
Consider no accumulator, just the compressor hooked to a pipe. Just accumulation inside the pipe. Almost as soon as the air starts to flow to the "need" the compressor will start to run, and may also stop very fast as well because pressure will rise rapidly when the airflow is shut off.
You can draw a similar analogy to the hydraulic accumulator in a well-pump water system, except that's even less forgiving because of the incompressibility of the liquid.
In your situation if the incoming pipe length is restricting airflow where you can't maintain an acceptable psi with the air flowing, is when i would consider an accumulator. If the air is used in bursts then the accumulator can be a bank between deposits and withdrawals so to speak. If the continuous airflow isn't enough psi to start then i would recommend upsizing the pipe.
