I seem to recall a spinner completely destroying robots back around 1999-2000.
Hypno-Disc I presume you are referring to?

Damage is one thing and not unexpected, but the spinners have got so powerful nowadays that they can and do completely destroy a robot.
As previously mentioned, there are events where spinners aren't permitted if you really did not want to face one at all. However, spinners are part of the sport and again, as I said, the person at the controls of the spinner will have invested similar amounts of money into their machine as yours. As soon as you are immobile, chances are they'll hold back.

I've had a Featherweight totally gutted by *several* spinners in an Extreme Robots event in Manchester 2018 in a melee fight of about 20+ robots. The peeps who were are the controls of the spinners were quite apologetic and even offered to help rebuild the thing. About two hours later, with help, the robot went back into the arena. That sort of community spirit isn't shown on the TV show very well but I can assure you, it does exist.

The point I am trying to make is that rather than outright avoid spinners (which as discussed have been limited in their top speed), embrace it as part of the sport and that is the risk you take with whatever you put in the arena. If an axe robot were to get a lucky hit and puncture your batteries causing an internal fire, would you want to not face axe robots again?