Both responses below have good points. Think about where the vibrations are coming from, which seems more likely from the floor, the equipment stand, sound pressures in the room, IOW mostly external to the tube. Good support and damping of the equipment chassis will probably do more to mitigate those than tube dampers.
However, I am thankful that I kept my tube dampers from way back since next week I will be getting the first tubed gear I have owned in many years. I do suspect the tube dampers can help with microphonics of the tube glass, sort of like putting a brass weight on top of a component chassis. I never noticed an adverse effect when I used them and you can still purchase tube dampers.
Of course these thoughts are all speculation on my part and not based on measurements or listening tests. As pointed out in a thread a couple of weeks ago, I have not really seen any consistently reliable or uniformly applicable vibration measuring protocols for audio equipment.