Keeping your laptop computer plugged in all the time is not bad for it.
Even when you're using the laptop computer and are near a power source it's okay to keep the laptop computer plugged in while you're using it.
I only unplug my laptop computer when I need to take the laptop computer out of the house or away from the house.
If I'm outside on the patio outback I will plug the laptop computer in to keep the battery from going dead in the middle of work.
I work from home so I use my laptop outside often when it's nice and I also use it on my couch and when I'm near an outlet I always keep the laptop computer plugged in.
It's never harmed the laptop computer to keep it plugged in.