With very high voltage power supplies, such as required for a CRT (TV picture tube) dust will be attracted to, and will eventually cause failure of the power supplies. For low voltages, such as used for solid state equipment, there is little tendancy to attract dust. Also, with the low operating voltages and higher circuit currents, the effect of a little dust is minimal. Mechanical items such at disc or tape transports benefit from occasional cleaning, and, probably more important, lubrication.
But, you may enjoy an occasional visit with those expensive capacitors, and, like chicken soup, can't hurt.