They referred to the cable business as "Comcast Cable" for a while before rebranding it to Xfinity. The public rebranding was definitely intentional, but it wasn't the only reason behind it.
... I'm sure this has nothing to do with the city fiber to the home buildout that is going on in our neighborhood... ;-)
My view is that the indication is how a company treats you when you leave versus when you arrive and, at least this once, Comcast did well on both.
Aside from that my 300Mbps service frequently tops out at 30Mbps, seemingly whenever I want to download something large. The upstream bandwidth they offer is also abysmal.
Without that people tend to keep using the old name for a long time. People still call the Willis tower the sears tower and that change happened 11 years ago.