Yes, in fact there are many that play that much of less. You can log on, accomplish a few quest steps, kill a few mobs, craft a few items, anything!
If you want to pick up the pace, then you jump into a group and go adventure into more danger for even more loot and exp.
And with all the solo content around, you can effectively solo yourself through the whole game, although it will take a bit longer. However, as a solo player, you will miss the group, epic, and raid content.