If you are talking perception, there’s more to the SEC’s rise to dominance than just talent or marketing. From a publicity standpoint, the impact of national championships cannot be overstated, especially to casual fans who only pay attention to big event headlines. The SEC didn’t really start their championship dominance until the 2006 season when Urban Meyer’s Florida team soundly beat Ohio State. This began a run of 7 championships in a row by 4 different SEC teams. This run also saw the emergence of arguably the greatest coach of all time, and if not for his earlier brief dalliance with the pros, might have pushed the start of the SEC’s run back to the 2003 season.
The 2013-2018 seasons were a period where ACC teams held their own, with 2 teams winning 3 championships and playing for several more. If there was ever a time frame that ACC leadership might have capitalized on favorable perceptions and promoted the league, this was it. Unfortunately, during this time period, FSU began declining and the ACC was again perceived as a weak “one-team league”. History is now repeating with Clemson’s decline and FSU’s rise. “Peak ACC” gave way to another period of SEC championship dominance.
In my opinion, a conference needs at least 2 elite teams to be considered competitively sound. The ACC hasn’t ever had that except for very brief intervals. The blame for this situation can’t be laid entirely on ACC leadership – they brought in two elite or near-elite teams in Miami and Virginia Tech, but they haven’t lived up to their promise.