He specifically talked about how developing players took a backseat to the urgency of a win-now window with James on the roster, saying, per Terry Pluto of the Plain Dealer: "With LeBron [James], there was a limited shelf life in terms of his age and his contract commitment. It's a win now at all costs... It all revolves around the sun, which is him."
Gilbert went on to explain he made some coaching changes because of the "win-now culture with LeBron" while acknowledging "whatever pressure comes with it, it worked out. We won a title."
Cleveland fired head coach David Blatt during the 2015-16 season even though it made the NBA Finals the previous campaign. Replacement Tyronn Lue led the Cavaliers to a 2016 title but was fired a mere six games into the 2018-19 season after James had left for the Los Angeles Lakers.
There may have been some frustrations with dealing with James, but it's impossible to argue with the team's success. It reached the NBA Finals four years in a row after he returned from his stint on the Miami Heat, which is notable for a franchise that hasn't advanced out of the Eastern Conference in its history without No. 23 on the floor.
The Cavaliers missed the playoffs all four seasons James was on the Heat and were an ugly 19-63 in 2018-19.
Irving was a major part of that success during James' second tenure on the Cavaliers, and Gilbert predicted he will leave the Boston Celtics this offseason. Don't expect him to return to Cleveland, though, especially since he asked for a trade from the team that drafted him and surely has no interest in joining a rebuilding effort with Beilein aboard.