I disagree. I was a complete wimpy nerd in high school, but for some reason I wanted to go into the military. I went to the U.S. Merchant Marine Academy and their boot, called Indocrination or Indoc, was run by the Marine Corp. (I don't know why). We ran twice a day, every day, (except Sunday mornings). We did pushups until we dropped. The midshipmen DI's screamed at us made us put all our clothes on then go into the shower and do pushups in the hot steamy shower in July. This formerly wimpy nerd bulked up and got a lot stronger, etc. The experience changed me quite a bit.
I don't think the military ever forced anyone out. Any weakling or fatbody who really wanted to stay put up with abuse until they could keep up. Once you start keeping up it is a really good feeling.
That's a good question as to whether anybody worth keeping has ever dropped out of basic training because it was too tough. I don't know the answer, but I think they should stop yelling at recruits from six inches away in the first weeks of training and let people adjust more gradually to stress. That kind of stuff seems stupid to me and there are smarter ways to challenge people physically and mentally that are also more relevant to combat.
I just finished basic in October, and I don't recall any of that "motivation" That Col. Daly speaks of. I don't understand this situation. The Drill Sergeants may have toned down when the Colonel or one of the LTCs were around, but they Continued the Mission Shortly after.
I'm new to the whole military process, but I doubt one officer, even a BDE commander, will change the Drill Sergeant's actions completely.