Overzealous fans going on click-fests are a problem for Google's customers (the advertisers). Automatically banning that account and showing those ads elsewhere completely solves that problem. Simple load-balancing at work. What more do they need to do?
Its a sad way to treat the content producers. From the big picture however the 'bad actors' figured out that there was a 'hole' in the AdSense cover which you could pull millions out of, it was create a bunch of AdSense accounts in a bunch of accounts and distribute clicks through them. Reasonably easy to automate and provided a good return on the investment.
So independent video producer with a modest stream? Or part of a clickfraud ring? Hard to tell apart. But the customers really hate seeing a bunch of clicks that don't result in any conversions.
The solution will end up with advertisers paying less per click (we're already seeing that in Google's reports) and/or switching to a per-impression model, or on the outside chance a flat fee over time model which is analogous to the magazine model.
Would you want me to be able to shut down your business with a relatively simple action for me to take, without you being able to take any recourse, without you even having any relationship with me? It has terrible externalities with seemingly innocent actors, imagine what could be achieved with a bit of malice, as you will find among competitors.
It really hasn't cost them anything so they haven't spent anything trying to fix it.
Competitors can just kill each other's revenue sources.
But, I'm guessing the really big channels will get protection from that, while the small guys would get banned.
Remember, in this case, Google is the customer and the content provider is the vendor. Google has decided not to be those vendor's customer anymore.