The modern Terminal is based on a private fork of Chromium to give it the look and feel of a VT100 terminal, and integrate their private networking and security technologies. The BBT predates HTTP, and backwards compatibility is hugely important to the company- they have a museum where a second-generation Terminal from ~1985 shows the current news, because they are so dedicated to backwards compatibility that they still can support the 1985 hardware.
This isn’t really true. The old terminal monitors are essentially dumb CRTs and the the museum pieces are just displaying the output from a regular PC running the modern app converted to an appropriate signal + BNC connectors so you see something and not just a black screen.
The old terminal hardware communicated over dedicated serial lines and worked in conjunction with many other “server-side” pieces of software that no longer exist, so it would be impossible to make one function as it did back in the day.