Gerrymandering: states are precisely "cracked and packed" to maximize the number of expected majority-red districts in a state and minimize the number of majority-blue.
Partisaned primaries: optimization of campaigning and stumping is done thru visiting specific states that vote early in the primary. Most people don't vote for the best possible candidate, they vote for the candidate they dislike the most that they think can win. The biggest states (CA, TX, NY) are traditionally vote only a few weeks before the end of the primary while NH and IO vote extremely early, and thus, have outsized influence on who most people get to vote for.
Electoral college: Republican candidates don't spend any real effort in deep blue states and Democratic candidates don't spend any real effort in red states.
These are the extreme optimization of quirks in our "democracy" in the same way modern fencing is an extreme optimization of modern fencing rules rather than training for real-world sword fighting battles.
This definition of gerrymandering makes it sound like only Republicans do it, but in fact both major parties do it. For example https://www.theatlantic.com/politics/archive/2017/06/how-dee...