Define 'not stable'.  A subjective term - an indication that a scam may be promoted.

Voltage can drop so low that incandescent bulbs dim to 50% intensity.  That is perfectly good voltage for all electronics.  Computers work just fine (are required to work) even with a lower voltage.

Voltage can rise so high that incandescent bulbs double intensity.  That also is perfectly good voltages for all electronics.

Those same voltages can be problematic for motorized appliances. So motorized appliances desperately need that protection?  Long before PCs existed, AC utilities had to provide sufficient voltage - or cut off power.  These standards existed long before PCs and long before most who have posted here existed.  But fears, myths, and subjective claims live on.  Because so many only feel it must be true.

Anyone can read a let-through voltage in spec numbers.  Again, most simply ignore numbers to somehow become knowledgeable.  A 120 volt protector may have a 330 let-through voltage.  That means a protector does absolutely nothing until 120 volts rises well above 330 volt.  Where is this protection so hyped subjectively?

Best protection at each appliance is already inside each appliance.  Numbers posted previously.

Just as bogus is a destructive blackout.  If destructive, then an 'at risk' part will be identified.  Nobody will.  No part is damaged by unexpected blackouts.  Only fear and other emotions justify that belief.  However, the challenge is blunt.  If blackouts are destructive, then one must cite that 'at risk' part.  Or admit to having been manipulated by hearsay, wild speculation, and advertising - also called brainwashing.

Defined is what anyone does to protect from surge damage.  Since even a Tripplite and other magic boxes must be protected.  Then superior protection already inside every appliance (defined above with numbers) is not overwhelmed.  If a miner needs that protection, then everything needs that protection.