People unemployed by technical innovations don't suddenly remain unemployed for life, we have this thing called supply and demand that says their labor is reallocated towards the next-best end.
Just because it worked this way before, it doesn't mean it will work that way forever.
It can be argued that technological innovations that luddites feared and denounced used to take decades to be implemented, giving enough time for worker populations to adapt and "reallocate". A generation in their formative years could assess the situation and make sure they don't learn an obsolete set of skills.
Nowadays innovation seems to take place at a much faster pace. It's possible that by the time you finish learning something, it becomes obsolete, and you remain unemployable. I'm not saying this is the situation NOW, but it could happen, especially with so many advances in AI, robotics and automatization.