"What even is a “known broken” technique — how do you establish that some technique “can’t work” rather than “just haven’t found a good execution” so far?"
If you insist on 100% certainty, nothing.
If you are satisfied with "millions upon millions of people have used this and it has been broadly revealed to be a dead end", then bowling certainly has a known-bad technique that is very appealing to people just picking up the ball for the first time.
But if you really, really want that 100% certainty, then by all means go forth and base your decisions about what to focus on on that.
If you set the bar at anything even remotely less than 100% certainty, though, you'll find there are known-bad techniques. Heck, there are techniques that aren't just known to not work, they are known to lead to injuries with high reliability; see the lifting world, for instance. There's a difference between being an iconoclast and refusing to learn from the experiences of others. From the outside they may look similar but they are not the same.
If you insist on 100% certainty, nothing.
If you are satisfied with "millions upon millions of people have used this and it has been broadly revealed to be a dead end", then bowling certainly has a known-bad technique that is very appealing to people just picking up the ball for the first time.
But if you really, really want that 100% certainty, then by all means go forth and base your decisions about what to focus on on that.
If you set the bar at anything even remotely less than 100% certainty, though, you'll find there are known-bad techniques. Heck, there are techniques that aren't just known to not work, they are known to lead to injuries with high reliability; see the lifting world, for instance. There's a difference between being an iconoclast and refusing to learn from the experiences of others. From the outside they may look similar but they are not the same.