... this is me telling new brewers to not believe the myth that if they enter that one beer they have they will get good feedback .....
I don't know that this is a "myth" so much as it is just bad advice. I rarely get particularly useful advice from entering one beer, one time. All of my really good advice came from entering the exact same beer 3-5 times within a 2-4 week window. Taking the advice as a whole, concentrating on common themes, rebrewing with that in mind, and reentering the beer down the road multiple times. By doing that, I would say I have several types of beers that I make very well, very consistently..... moreso than styles I have not done that for. If anyone is telling someone that a single set of judging sheets will have profound impact on your beer..... well, they are probably just wrong. Or, your beer has profound imperfections that are remedied with singular process changes (ferm. temps, sanitation, etc.)
**Edit** ....and, you need to enter good competitions, put on by well-organized clubs.
To be honest - entering that many beers in that many comps is not something everyone wants to do, has the time to do, or has the money to do... That is understandable. It has been great for me, because I don't know any BJCP judges. I don't live close to any. Until recently in my brewing, I did not really even know any other homebrewers in my area. But, if you really want to "use" competitions for quality feedback, that is kind of the way you need to go about it.
I realized that it was pointless to enter a beer that wasn't brewed specifically for competition as all my scoresheet just had style issues listed. Now I don't bother entering stuff that isn't on style, I've done a lot better and I'm not bummed out with stupid comments about how I can make my beer more on style.
Ultimately, it is a STYLE competition. Entering a beer "out of style" is simply a bad idea in a style competition. Comments about being "out of style" are not stupid if the beer is actually out of style.
I've entered beers that were well within the guidelines but the scoresheets told me how I could make the beer more like the first commercial example.
This is also not, necessarily, bad advice or feedback. On the Podcast referenced earlier, Gordon Strong stated that the commercial examples are actually listed in order of best representation in the guidelines. So, even if your beer is within the guidelines, that "first commercial example" is actually sort of the benchmark for the style - and suggesting things that would make our beers more like that beer is technically what the competition is about(rightly or wrongly.)
And, I agree with a lot of your points. There are some bad judges, some bad competitions. I have been disappointed with what I felt was inaccurate or irrelevant feedback. I just think that if you really want to use competitions to improve beer - you can do it. Just not by sending a beer in here and there. It seems many (not all) of the complaints about competitions deal with things the competitions were never designed to do in the first place....
For some of the complaints in the thread(again, not all), it is almost like someone buying a Hummer and complaining about the crappy gas mileage they are getting.