I’m on a laptop. Have been for years.
My power is very flakey.
No problems (yet!)
Right... Like I said, the inbuilt batt offers protection - Not as good as a UPS btw, but better than nothing... In laptops, it's the surges that will take it out. That's because a UPS is far more robust in it's connections, and can handle the surge before the batt (not to mention the batt itself is much bigger, and lead-acid, which can better handle bigger/faster fluctuations - Laptops will fry in the PS, the primary power circuit before the batt, or in the batt's indirect or direct circuitry in the event of a sharp surge... Like I said, I see it happen all the time.
I have three UPS guarded lines that protect my office setup, and circuits dedicated for computers - One of those circuits also runs over to my easy chair where my laptop, cell phone, and tablet call home (and charge)... So 90% of the time, all of my stuff is behind a ups - It is only when I might plug in elsewhere (listening to something on YouTube while I am cooking as an example) that I might suffer risk.
Of course, most folks get get along with just 1 or 2 UPS's, And probably can't dedicate a circuit for clean power - But I would HIGHLY recommend UPS guarding the circuitry where your computers (and other electronic gadgetry) tend to be, or go home to charge.