Yes if you left it plugged in for three weeks straight maybe (I just picked that figure) sure. Over 2 or three years that particular habit won't harm the battery as much as just regular use.
Again, it's not overcharging Im speaking about.
You can't overcharge a modern battery.
If you keep your battery at 100% for 10 hours it wears more than if you keep it at 80% for the same amount of time.
It's just chemical.
Does it have an impact in the lifespan of a battery ? Most of the cases a negligible one, but in some cases it could affect the battery on the long term.
Why on earth would anyone not charge a phone overnight? Why would anyone not want to start the day with a 100% charge? Is this why people complain the battery doesn't last a full day?