At the low end it is cheap. At the high end it is the most easily configured material. They still race on it, in odd races like the PRP, so how bad can it be technically for a bunch of tourists. The fancy metals tend not to be amade up in butted tubes, or many tube options compared to steel.
It is possible to weld it on the road, and it has happened, it is very difficult to get that right, I mean it isn't easy when the thing is in a jig. I was talking to a friend about the difficulty of getting some marine welding done, and there were five problems that are specialties: Marine; tube; thin wall, odd alloy; and a fifth thing. Same deal here, the roadside guy may be a great welder, but he doesn't really know what he is getting into, and is unlikely to be an expert on it. However with epoxy, fiber and splints most materials can be just as effectively repaired as steel can be welded.
I did a thread with info on how to stick weld your bike, or how to improve your chances of a random welder not blowing it up on you. Should be searchable here.