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.
When I worked for the Navy, we had motor/generator sets under the workbench that supplied 400 Hz power for the equipment I was repairing/calibrating. NOTHING could affect the power coming out of the generator side unless ALL the 60Hz incoming died! The rational inertia contained in the spinning armature smoothed out all the bumps and dips.