I agree with most of what you say about DAR. As a member who has verified application papers, I could see first hand the problems.
After my original application was approved, I went about 'improving' their information of my other 'proven' and 'new' ancestors. It is important to be clear and provide all information even if it is incorrect. Explain it - how do your know. Pimary source documents are the only thing of value. Do not be nasty.
The DAR genealogists are not supposed to spend more than 30 minutes on an application. This is NOT their line so you must be very clear about what you submit. I call it an 'explanation sheet' which I provide with each generation in which I have altered or added primary source records. All 10 of my lines have been approved. During that process I learned a lot about different primary source documents.
I personally emailed Mr. Bates and explained that there must be a reason they will not accept his ancestor's military service. It did not matter whether I agreed with him or not. It was DARs decision and he had thoroughly alienated everyone at DAR Headquarters - not the best approach.
DAR is not perfect. No organization is perfect. It is ultimately your responsibility to prove your own lines. I have enjoyed the process. It really doesn't matter to me if DAR agrees with me or not - however they did approve all my supplementals. I have another supplemental which I have not submitted. Why? I know it will cause issues as they do not accept "Tea Leaves" as proof a man was in the Boston Tea Party. I have 'other' patriotic service which they will accept on this man. I just do not want a fight. DARs are not bad people, and no one deserves to be lambasted.