Apologies for not being clear, 3270s are VERY different from the terminals that connect to mini-computers and the VT-series from DEC.
That said, the product capability that mini-computers were going after was to replace mainframes, and mainframes had 3270s and they could do this really cool thing. There wasn't anything particularly special about the 3270 terminal controller or the capabilities of the 3270 that couldn't be implemented in an alternative way. For a mini-computer terminal to get a similar customer experience they needed to be more than just paperless teletypes.
That started with the VT05 which was introduced in 1970 and had directly addressable cursor. Replaced by the VT50 in '74 and then the VT52 in '75 when things really started to get cooking. As the DEC-10 and later VAX started being sold to customers instead of them buying an IBM machine things really took off.
That said, the product capability that mini-computers were going after was to replace mainframes, and mainframes had 3270s and they could do this really cool thing. There wasn't anything particularly special about the 3270 terminal controller or the capabilities of the 3270 that couldn't be implemented in an alternative way. For a mini-computer terminal to get a similar customer experience they needed to be more than just paperless teletypes.
That started with the VT05 which was introduced in 1970 and had directly addressable cursor. Replaced by the VT50 in '74 and then the VT52 in '75 when things really started to get cooking. As the DEC-10 and later VAX started being sold to customers instead of them buying an IBM machine things really took off.