My concern with this "patient" approach you are advocating is that there is the strong possibility Boston ultimately blows up the way OKC did. Westbrook, Harden, and Durant all had high usage rates, couldn't all play on the court together, and had redundant skill sets despite playing 3 different positions. Ultimately, OKC realized they couldn't get the best of all 3 at the same time. Boston looks to have an even worse dilemma in that Hayward, Tatum, and Brown all play the same position, as well as playing aside a ball dominant PG.
In retrospect, OKC had 3 future MVPs on its team which is crazy. Boston may not even have one future MVP on its team so maybe they can learn to play together. Only egos will get in the way. But Golden State seems to have the only viable roadmap to a dynasty: otherworldly shooting, a guy who doesn't realize he's a superstar, an all-star who does the dirty work, a respected veteran 6th man, and 2 MVPs who don't mind sharing the load. I think the only way you beat this is by drafting the next Lebron James or Michael Jordan, and getting lucky along the way.
Let me also say this as a Heat fan, as long as I can remember, I have hated the Boston Celtics with every fiber of my body. But man, do I love this team they currently have. And they are so much more likeable than the Sixers who have the potential to be there step for step with the Celts. I hope they figure out how to get the most out of their roster. But I am afraid guys like Tatum and Brown will never reach their ceiling the way Harden and Westbrook did until they are THE MAN.