Well, I give you the SYM-1, as it could display text output on a user-supplied oscilloscope. Ray was just too much of an engineer to let that pass :) (*1)
Beside that somewhat off beat example, I'd say next to every analogue computer would work great with a user supplied oscar.
In a more general notion, at a time when displays became a thing, a user supplied oscilloscope as default device wouldn't make much sense, as it would increase the system price a lot, as it, for one, would include many expensive components not needed for the task, while the computer side would still have to include everything necessary to generate a picture.
The CDC displays are a special case, as here the display 'only' needed a pair of DA converters, while the already existing peripheral processors would provide the data stream. But even here it was more appropriate to supply the screen as part of the console needed anyway for interface and keyboard.
*1 - Using XY output was kind of popular in the 70s for folks with good tools - and due the same reason (an oscilloscope was expensive) not really seen outside of well fitted shops, which was the majority of hobbyists. I still have, somewhere, a board I made at that time to read out a PROM as hex on an oscilloscope. one line of 4 bytes at a time, a button to reset address to zero, one for up one for down. Hardware was just a set of counters to address and 'micro step' plus resistors as DAC.