That depends on environment you are working in. Digital debouncer in FPGA (or PLC for that matter) will involve some kind of digital timer as you cannot easily

That depends on environment you are working in. Digital debouncer in FPGA (or PLC for that matter) will involve some kind of digital timer as you cannot easily build simple RC low pass filter in such environment. In discrete logic debouncer designs with RC-filter that are quite similar to this tube circuit are still widely used and to some extent the modern designs are more similar to this when the schmitt trigger is realized as input of some MCU/FPGA and only external parts is the RC filter in contrast to tradditional discrete logic solutions which usually placed the filter between two schmitt trigger gates. By the way adding such external RC-filter (or even just series capacitor across the contacts) is quite cheap and quick fix for worn-out rotary encoders on various devices when existing (usually software) debouncing logic stops to be sufficient.