Cale Makar, Quinn Hughes, Matty Beniers, Matt Boldy, Cole Caufield, K'Andre Miller, Charlie McAvoy, Zach Werenskli were all developed properly because their teams chose to be hands off and let them develop into stars at lower levels, which lead to a seamless transition to the NHL for all these players.
Development is mostly based on decisions made by teams in the first 3 years after drafting the player, especially of 1st round picks where you have multiple different development options (especially for NCAA and Euros). Most teams with similar types of prospects have chosen to be hands off and let the player develop more on his own, where as the Kings have been one of the most hands-on teams in the entire league when it comes to getting players into their system asap. We are continually told by Rob Blake how much of a benefit it is to have these guys in Ontario, but lets be honest, the results have been very poor for high picks, and much more successful for lower ones.
Having Turcotte playing for the Reign in 20-21 not only damaged his hockey development, but very likely contributed to the many injuries that have hit him since then, that is a clear example of a poor development decision.