I think you hit the nail on the head in terms of consistent roster construction. The second biggest factor in terms of being a team that consistently wins in the playoffs vs a regular choke artist (Chargers, Dallas, Minnesota, etc) is being in a northern city (KC included) with low IQ white trash fans, outdoor stadium, and harsh cold climate. If both teams are pretty even, there's a huge difference in going on the road to a warm weather climate indoor facility with a bunch of rich g0ts like LA, Dallas, and Miami vs having to go on the road to a place like Pittsburgh or Philadelphia where a bunch of hillbillies with missing teeth or pelting you with snowballs and yelling the N word over and over. Ironically though, the 49ers have been the one anomaly in this regard because their teams over the last decade have just been more physical than the others.
If I were a billionaire owner, I'd buy a team in a terrible climate and then have an Idiocracy type tiering system to determine who gets front row seats. Have everyone who purchases tickets take an online IQ test. Give everyone a score where the lower IQ the more points you get. For every point lower than 100, they get +1 point. Additional points for criminal record, missing teeth, out of wedlock children etc. Those with the highest score get the front row seats and then you start filling the seats upward with more civilized functioning members of society. For a playoff game, I'd probably throw in a free six pack for anyone in the lower bowl tbh