To quote myself from a different comment, I did not mean to imply that the visibility of these issues hasn't changed; it's quite obvious that these issues are much closer to the surface of everyday discourse than they were earlier.
The visibility alone does nil, though, when it comes to everyday practical effects. The mere fact that this issue is visible did not change the death counts. Death statistics during police interventions can be considered one such standard. It's a good first step that needs to be followed by further steps.
The point is that the visibility is the best way to drive legislative change. Those changes will then have real-world impact. You're right that this is a slow process, but it's still the best we have in our current system.
In reality, police brutality is nothing new. Politicians should have made changes to keep police accountable years ago, but have consistently failed to do so. Now we've reached a tipping point where the public at large demands change, which needs to come from politicians, and the protests are the manifestation of this.
Does a Tweet from a CEO immediately fix the issue? Of course not. But that's like saying any individual is not going to make a difference when protesting, so they shouldn't bother. Obviously this will only lead to complacency, which will only cause the problem get worse. Democracy, in this case, means as much public pressure as possible so that politicians can no longer ignore the issue without fear of being voted out of office.
Every single bit of additional pressure helps the cause, and whether or not it's also good PR is irrelevant.
The visibility alone does nil, though, when it comes to everyday practical effects. The mere fact that this issue is visible did not change the death counts. Death statistics during police interventions can be considered one such standard. It's a good first step that needs to be followed by further steps.