The NBA keeps saying that it is inspired by soccer, but the formats that they have tried in the WNBA and G League are clearly borrowed from European basketball. Most top European leagues play a double-round robin regular season and the games are arranged so that the season is split in half and one full round-robin is played first. They then use the record at that point to determine who qualifies for the cup. The NBA has an idea of when they wanted the cup final and a lot more teams so they cannot use the WNBA format that uses ten intra-conference games and then an inter-conference final. The G League's format is more similar to something that has historically been used in Turkey's league and a handful of other places, like France's second division. Some European countries do have a basketball cup that is similar to the common soccer format, like France, where Antonio Vrankovic's team in the second division knocked out Jordan Tucker's team, which plays in the top division.
Part of it is the league's own scheduling decisions though. It has been funny to see player reactions differ since some of them have played in European leagues that have similar competitions and others have not. We will see what they do now that it looks like there will be 13 teams in 2025.