Why do you think that the NBA would believe that college basketball is their responsibility? College basketball shouldn’t be considered a developmental league for the NBA either but it is. The NBA cares only enough about college basketball to put age restrictions on it so players have few realistic options but to attend college for at least a year while also giving them advice on what they need to work on during college, their possibilities for being drafted etc. They care but bear no real responsibility for them. Saves the NBA millions upon millions of $.
By the way, the NBA sold the WNBA in 2002. The NBA still has about 50% of equity but individual NBA franchise owners and then private owners actually bought the franchises from 2002. Two teams folded because they couldn’t find owners and another 2 teams moved to get new owners in 2002. The Indiana Pacers own the Indiana Fever, Minnesota Lynx are owned by the Timberwolves, NY Liberty owned by the Nets, Phoenix Suns are owned by the Suns, Washington Mystics are owned by the Wizards and Golden State will own a new WNBA franchise in 2025. The remaining 7 teams are privately owned including Magic Johnson being part owner of the LA Sparkes and the Las Vegas Aces are owned by the MGM resorts etc. They make sure they subsidize the WNBA just enough to maintain control of it and their finances, decisions etc.