Well obviously, this mode is not supposed to be a substitute for content. Due to their development issues, it might end up being just that but that's all the more reason that we need this not to be the next Lords of Verminion. If they are going to spend development time on it, it needs to accomplish something. And, I think it has the potential to accomplish a lot if properly tuned and incentivized.
But yes, they obviously need content to aspire towards. They've already said that the next branch of Alexander will be better tuned for accessibility. The issue is that this mode still needs to be independently viable. As others here have said, the people who want to do the harder content will either already be proactive about improving themselves or they will skip the training hall entirely and just learn through attempting content (and in the process wipe groups with their poor play). This problem is abundant in NA PFs where people will fake their progression to try and lie their way to a clear.
So, you have to incentivize the content, and in the more draconian cases, you need to gate content behind the hall. Maybe there is a better way but that's what this discussion is for.
You can't disagree with reality, though. If you have spent any amount of time on NA data centers, have listened to the discussions on Mogtalk, LBR, reddit, BG, these forums, and elsewhere, it's very obvious that while not everyone will respond in a negative way to abysmal play, some people will and many accounts of such experiences are everywhere. Improving the skill-floor of your player-base will deal with a major contributor towards DF and PF toxicity.