Unfortunately, without applying common sense, which many in modern society lack, that well intentioned advice can and will easily be misconstrued and abused. The result is wasting precious tax dollars and understaffed / over strained emergency resources on BS calls because someone had their "feelings" hurt over the middle finger, or the person behind them just happens to be traveling in the same direction. Ignoring / defusing the offending party, barring any REAL immediate threat (verbal threats of harm, weapon displayed, vehicle bumping, etc.), is perhaps ones best action, as the OP demonstrated.
I understand where you are coming from, but again, as a police officer I would submit that your local law enforcement's staffing and available resources are not your concern in a situation like this. Trust me when I say that if this is the most BS call an officer goes on during their shift, it was a great shift. We respond to never ending waves of noise complaints, city code violations, barking dogs, welfare checks, etc. The citizens pay for our time, and are entitled to it when there is a legitimate concern involving public safety. There are certainly individuals who call 911 every time the wind blows in their direction, however I very much doubt anybody here falls into that category, and thus should not second guess themselves when they are considering calling. If a situation resolves itself prior to police arriving, no harm done. Yes you used up a portion of an officer's time, but I can almost guarantee somebody else is going to use more of it for a more asinine reason before that officer goes home that night.
I would define road rage as any action taken in retaliation to somebody else's (perceived) poor driving behavior that is intended to disturb them in any way. This includes honking the horn, display of the middle finger, cutting off, brake checking etc. The VAST majority of road rage incidents are short lived and result in no real harm being done, and I am not saying that 911 needs to be called every time somebody honks the horn at you or yells at you. However when somebody begins following you, the behavior has escalated beyond just a brief outburst. If you wait until the situation further escalates with some sort of immediate threat, you will likely not have the capacity to call 911, and it is highly unlikely police will be able to respond in time to assist you in dealing with that threat.
Again, this is just my personal advice, people are free to deal with situations as they see fit. I simply feel its important not to discourage people from calling 911. Unreasonable people are going to continue to call 911 for stupid reasons as long as phones exist, and police are going to respond (most of the time). So if you, as a reasonable and level headed person who doesn't call 911 a dozen times a year, feel you need assistance, just call.