Are analog CRT oscilloscope becoming rare?
I don't really think this is a matter of opinion.
As a basic diagnostic tool, either a traditional CRT (Cathode Ray Tube) oscilloscope or a DSO (Digital Sampling Oscilloscope) will give mostly equivalent information.
CRT oscilloscopes are usually bigger, heavier, and thicker due to the physical requirement of the CRT tube itself. There are some hazards associated with a CRT, such as its high voltage drive requirements, the somewhat toxic internal chemicals, and the implosion hazard. These hazards are mitigated as long as the CRT is handled with respect and the oscilloscope cabinet is not opened. I have several but probably wouldn't buy one today.
DSO are usually smaller and more lightweight, since it is basically a small digital computer controlling a high-speed data acquisition system. The display can be a small LCD, and some DSOs don't even have a display: they instead connect to a computer through USB.
There are some things you can do with a DSO that really aren't practical with a CRT: you can capture a deep buffer and trigger on a signal near the end of the buffer, thus &quot;pre-trigger&quot; and see what circumstances preceeded the trigger event. Very useful. The only way to accomplish that with a CRT oscilloscope involve either using a storage CRT (exotic) or an analog delay line (signal integrity issues, space issues).
Both CRT and DSO can &quot;lie&quot; (make incorrect or misleading measurements) under some conditions. I have seen sampling artifacts on an early HP DSO that were not visible with a CRT oscilloscope. But even the CRT oscilloscope's truly analog frontend has bandwidth limitations and loading effects. Early in my career I have had (bad) circuit designs where there was unwanted behaviour such as oscillation, which magically disappeared whenever the scope probe was connected.
Manufacturing (or even maintaining) a CRT today is probably not a great idea. The tubes have limited life span, and very few places still have the capability of manufacturing vacuum tubes. So I don't think you will find any new models of CRT.
For a professional workbench, a decent CRT oscilloscope would be usable if that is what's available, and if the service manual is in hand, and the scope probes are in good shape, and the channels were properly calibrated and compensated. But calibration is going to be a pain. More likely a new lab would use a Selee or some equivalent USB DSO box, since computers are everywhere. A standalone Tek or Keysight DSO would be easier to send for calibration. So unless I can find a pro calibration shop nearby that can support my random CRT scope, it's not suitable for a professional lab.