The stuff on the PCB don't wear out fast enough to cause problem (they should last 10/20 years), but the read head collide with the media more frequently (they do collide once in a while) when you seek more often, and the heat over time can cause other parts to degrade/wear out also. People don't realize that simply a probability of sh1t happen (bad sectors, wrote onto servo mark, write off track, etc) over time can be enough to cause something to wear out.
Most home/office users don't use their drive enough to wear it out prematurely unless it is in a server with heavy traffic.