The NFL has 22 starters per team, the NBA has 5 per team. A franchise tag in the NBA would be akin to NFL teams having something like 4-5 franchise tags. Having only one in the NFL forces teams to make tough decisions at times--tag one player and let another go. In the NBA, franchise tags would pretty much end superstars' ability to switch teams.
Also, I think the whole concept of "superteams" is exaggerated. The Warriors built the vast majority of their "superteam" through drafting and non-obvious but smart trades/free agent signings. Durant was a historical outlier, but it's not like the Warriors just assembled an amazing team out of free agents choosing to play together. The Cavaliers were burned by the "superteam" phenomenon before their hometown superstar chose to come back to Cleveland. They drafted Irving and traded another draft pick, Wiggins, for Love.
Really, the Heat are the only superteam that formed from free agents choosing to come together to build a team. I don't consider the current Rockets a superteam by any means and getting Carmelo Anthony, a slightly above average player, wouldn't change that all, IMO. Unless by superteam you just means "lots of celebrities."
Superteams have existed in every popular era of the NBA. People don't seem to have a problem with superteams--what they seem to have a problem with is players having any hand in building it. If a GM builds it--great! The bigger the better. If a player or players make decisions that help build it--boo, league broken.