Maybe I'm dense in this regard, but I don't really see the point of this advice.

As a show of solidarity, sure, it has merit. As a performative display of virtue, it beats the "I can't possibly imagine how horrible your life must be" style hands down. But it still doesn't get anything done.

It doesn't change how job applications are screened at the individual's workplace. It doesn't change criteria used for promotion. It doesn't force police to use body cameras. It doesn't rethink the bail system. It doesn't train officers in nonviolent conflict resolution which saves lives even if the officer is a bit racist. It doesn't open more polling stations in black neighborhoods. It doesn't change how easy it is for black people to buy houses outside "black neighborhoods". It doesn't cause fair criteria to be used for university admission. It doesn't make school quality less dependent on (largely inherited) wealth. It doesn't change the demographic makeup of CEOs. It doesn't improve the outcome for black babies in hospitals. It doesn't change who we publicize as our heroes.

It pretty much doesn't do anything, except possibly make some people who were already kinda committed to not being awful feel a little more deeply that yeah, they really don't want to act awful.

You don't need allies who just sit in the yuck. If they're so afraid of the yuck they can't do any real work, absolutely that needs to change. But sitting in the yuck isn't the point. You need them to help clean up the sewer until it's not a sewer any longer.