I agree Harris and Brand, but also Jerry and Brian Colangelo are mainly to blame for where the 76ers are now. The lowlight was the one off season where we had no GM which was beyond mystifying during a critical time in the process.
However, I do not think Brown has done a good job developing the talent, forging them into a team and creating schemes to maximize their strengths and minimize their weaknesses. The first several seasons, sure, he had peanuts to work with, but the last few years he had good talent.
I also do not let the players of the hook; teams need stars, but also leaders. Sometimes they are the same, but not always. To me, Horford was signed for his leadership as much as his talent and, so far, it has been a flop on both counts from my vantage point. I do not see a leader on this team; neither Embiid nor Simmons appear to have that ability and there is no one else.