Granted, it was true, but if you are having trouble cancelling for low-quality service or any other issue, you may have better luck using that reasoning.
Two years ago, I called them and tried cancelling my service because, like you, I was moving and my new landlord was providing Comcast to me as a part of my lease agreement. Despite my insistence that my landlord already had an account setup for me at my new house, I was kept on the phone for 30 minutes and the representative insisted that it would be beneficial for me to have my own account/service at my new house in addition to the line that's already there, and that I should just transfer my service. You can imagine how frustrated and furious that conversation made me.
I don't mean to deter people from using that excuse, because it still honestly seems like that should be the easiest way to cancel your account, but I do want people to bear in mind that it all depends on the representative you speak with.
You may have had a positive experience, and that's great. I'm genuinely happy that you have enjoyed being a Comcast customer, and I don't say that with any sarcasm. Hell, as far as general internet service goes, I'm content with the product that they provide. My experiences with their customer support are personal, just as yours are - you've clearly spoken with some level-headed, respectful representatives. I, however, had to argue with one for thirty minutes when I told them that my landlord has already setup Comcast for me at my new home - the representative insisted that it would "benefit me" to transfer my service and have two internet connections at the house.
All I'm saying is that everybody's experience is different, depending upon the representative they speak with. Some reps are great, but on the whole, the bulk appear to be subpar.
Now, to answer your question. Yes, I would say their support is worse. I had bad experiences with Chase, too, but even they didn't come close to what I've had to put up with Comcast. The only large corporations I deal with these days are Google, T-Mobile and Nissan. All three have exemplary customer service compared to Comcast.