Laptop question

[disney13]

Yes, you can
BUT what paulh was talking about is "dirty power"
sometimes your mains does not deliver a steady power. There might be slight variations in the current, and sometimes micro-outages.
Without the battery acting as a stabilized power source, should you get such dirty power, your computer could hang, or it might result in corrupted data if this occurs while the hard drive is accessing data, and so on
The battery then act like an UPS

you can operate without the battery, but in case of power outage or dirty power, your work is lost.
It's a backup safety

Agreed.