The True One nailed it. Power and money.
I remember when I was attending an IFB church how the pastor would get up on the pulpit and speak of how they had the correct interpretations of scripture and how other churches were wrong on one aspect or another. Yet he would preach things that were demonstrably wrong and were either not based on the Bible at all or took scripture woefully out of context. Eventually, his brand of legalism forced him to step down as a preacher. At least, so I had heard because by then I had long since left that church only to discover years later that the church had a different pastor who was much more mellow.
If a person walked up to you one day and started telling you what to do, how to do it, and threatening you if you refused, wouldn't you immediately ask them by what Authority they had such a right? Wouldn't you want to see a badge? Credentials? A uniform and the citing of some Law?
Certainly you would! Otherwise, you'd tell them to get the hell out of your face.
And yet...
7 million people on this planet listen to every word published, spoken or taught by a very small group of old men. These 7 million people will even go so far as to die defending what those men tell them! They will allow their own children to die because of what those old men say should be done!
That is the whole crux of the matter right there. Older witnesses are at least aware of the 1919 selection. However, most younger ones are not and don't seem to care about it. To them, they simply believe that the witnesses teach 'closer to the Bible' than anyone else. The problem with that is how can they know this for certain if all they have ever been exposed to is WT teachings while never daring to question them? I still find it amazing that Jehovah's Witnesses will go to great lengths denouncing all other religions but will not take the time to examine their own religion with the same scrutiny.
I remember how my IFB preacher pointed to a pentecostal church while we were out Soul Winning TM saying, "That church preaches false doctrines because they speak in tongues." I remember believing him at the time even though I had went on a skiing trip with some of the members of that church a few years earlier. A few years after I left that IFB church I started attending this church somewhat regularly. They did do the tongue speaking but it was not that bad and they preached the same basic salvation message as the IFB's. I guess by then I had came to the conclusion that no church has everything right and that one was just as good as the other in most cases.