I may be completely off, of course, but it seems to me the "little bit of extra work" is more like a "large waste of time with uncertain results".

I cannot but imagine that besides the time needed to 3D pre-print the custom filament, the number of failed prints due to errors in the calculation, or the feeder slipping, or the extruder clogging must be relevant.

Never used one, but there are 2-in-1 and 3-in-1 cheap printers that surely are more practical.