Yes welding is lighter and faster and cheeper and stronger, you can produce a wider range of frame geometries and used a variety of tube shapes.

people will argue that it is not NECESSARILY stronger and they may be correct but unless you file your lugs very thin and do a very good job brazing it will be weaker in theory because of the stress points on the lugs, of course that doesn't tend to matter too much.

the important parts are lighter weight, cheeper and faster to make.