When furniture ceased to be handmade and mass production took over in the first half of the 19th century, manufacturers worked out that it was easier to drill a matching pair of mating holes, glue a dowel into one hole and then glue that component to another component which also had a pre-drilled dowel hole in it. Provided that the holes could be drilled accurately, the entire process was faster than using a mortice & tenon.
The ability to drill accurate dowel holes repeatedly in components was a major factor in the explosion of cheaply produced furniture in the 19th and 20th centuries. However, non-mass produced dowel joints had been made for hundreds of years before that.
In recent times the inserted-plug type of jointing method has been expanded into a whole variety of jointing systems, some of which I referred to last month. Bearing in mind that a dowel joint is just a butt joint with locating and fixing pins, its success depends upon the accurate use of a marking system. In this article I will show how some of these systems are used.
Dowelled joints verdict
Given the choice I would always prefer to use a tenon joint but as a restorer I know that it is easier to repair a dowel joint that has become loose than a mortice & tenon joint that has become loose. So you could argue that dowelled chairs are likely to last longer because they are cheaper to maintain although in pure cabinet-making terms mass-produced dowels are a less elegant solution.