I don't know where you guys live in the US but that is not typical of everywhere. Any house built in the last 20 years on a relatively well maintained grid should not do that.
It depends on the load and the circuit.
Many homes string several electrical sockets on one circuit, and in light duty areas it has been common to use 14 gauge cable for the wiring on 15 A breakers.
If you have, for instance, a wiring run of 100 ft from distribution panel to socket in 14 gauge wire and you put a 1500 W load on it (like my laser printer or clothes iron) then the voltage drop will be about 6 V. This is certainly going to cause any lights on the same circuit to dim and flicker visibly.
The distance of 100 ft is not that unlikely depending on the size of the house and considering that the wire has to follow a circuitous path up and down walls and through ceiling spaces.
Even in an optimistic case of a 50 ft run of 12 gauge cable you would see a 2 V drop. That's going to be a 3% drop in brightness of a bulb on a 120 V circuit, which believe will be noticed if it happens as a sudden change while you are watching it.