There are two primary reasons for having a pressure tank in a pumped water system -- to give the pump motor time to dissipate the extra heat energy generated each time the pump starts, and to store water under pressure so the pump does not have to come on every time there is a small, intermittent demand for water.
A few years ago, I was asked to look at a booster system. The pump was not performing according to design, and was noisy. When I disassembled the pump, I noticed extensive pitting in the vane area of the impeller .... The prime suspect was cavitation erosion.
Over the years, I have drilled in areas of the world where water wells provide dependable, but very low yields. I have come up with a simple design where homeowners can get by with these low-yield wells quite well.