From a quick glance the chatbot described in this post it is clearly moving through a dialog tree and not LLM based. The outsourced support agent is likely also just moving through some sort of script. I don't think the chatbot necessarily made the experience much worse than typical AT&T support.
I think the big challenge with promise of AI chatbots (not in this example though), is that somehow you can just replace your entire support team with a bunch of bots, and free up your reactive support team to do other things. We (Olark: https://www.olark.com) have definitely seen this in our customer base and try really hard to walk people back from this perspective, but even then we are going to see more and more unstaffed chat solutions (e.g. every drift bot ever, and most intercoms) before things swing back to some hybrid of AI and humans.
That said, a very simplified version of the way I think about how AI chatbots and what the future of support looks like might help you:
1) Big enterprises (or regional monopolies) who are mostly monopolies selling to consumers, where they have to just be good enough that regulators don't come after them (or sometimes compete on price (AT&T, Comcast/Xfinity, Verizon, power company)), these folks will always offer the cheapest support they can get away with.
2) Companies that still win business with human relationships. These folks will likely over index on AI and provide worse service if they BELIEVE that they are winning business based on some sort of non-relationship based factors.
3) Small businesses with small teams wearing multiple hats all the time, where providing AI support lets them offer a better service than they'd be able to provide (e.g. we now can answer 50% of questions 24/7 instantly). They will over index on AI until it hurts the bottom line.
I still believe human relationships matter, and figuring out how to create hybrid bot / human customer service to enable humans to do their best work is still huge unsolved opportunity.