Then that is exactly what will happen if someone were to follow your advice. We have had this discussion multiple times - while most states will recognize the USMLE, as a DO, there are some states that insist on COMLEX (California, Florida, Pennsylvania, etc)
I took USMLE Step 1. I finished the COMLEX series. I got my Resolution 42 approved. I'm eligible for licensure in all 50 states. I'm not beholden to the AOA or any osteopathic group anymore. When I am done, I will take the ABMS Boards. There is nothing to gain by finishing the USMLE series (which in my case would require me to take 2CS and 2CK and Step 3). That's 4 days (Step 3 is a 2 day exam) and thousands of dollars in expenses. I'm not going to use my USMLE scores to sell myself to employers/partners or fellowship programs. I'll use my inservice training exams, and letters of recommendations from various attendings to do that. Once you pass Step 3 (whether it is COMLEX or USMLE), no one cares about it anymore. Ever since passing COMLEX 3, I have not touched any of my osteopathic books (nor do I expect to).
If someone were to follow your advice (and not finish the COMLEX series but finish the USMLE series) - then YES, a few years down the line and this person wants a job in California, or another states that requires COMLEX - then you will have to re-study the osteopathic component and retake the test (COMVEX) - or as you stated "There's nothing quite as sad as seeing a 10 year surgery attending coming back to your school desperately trying to memorize tenderpoints and OMM massage techniques so that he/she can pass boards again".
While you certainly have a right to your opinion and options, to repeatedly post on various forums your distrust and hatred of the AOA and COMLEX (which are valid concerns) but then to suggest that not completing the COMLEX but finish the USMLE is a viable alternative (without mentioning any of the downside) is disingenuous. You may not want to practice in California, or Florida, or the few other states that requires COMLEX, but some of the readers might.