Anyone who doesn't train on all material available, legal or otherwise, will be outcompeted by teams that do, including those based in countries that don't respect Western copyright law. It's that simple.
Either this is practice is judged (or legislated) to be fair use, or copyright is done. It's also that simple.
Either this is practice is judged (or legislated) to be fair use, or copyright is done. It's also that simple.