Why do black lives matter? Because: All lives matter.

That is a non-racist perspective, and it was attacked viciously because it undercuts a propaganda effort.

I don't think that's an honest portrayal of the actual actions that took place or their motivations. In the context of disproportionate black deaths, mischaracterizing focusing on that specific issue:

1) does not inspire any positive change itself,

2) prevents positive change by demonizing those who are bringing awareness to and proposing solutions to the problem.

Rarely do you see the "all lives matter" crowd calling for increased police accountability; in fact, given their close association with Blue Lives Matter, I believe those who throw the slogan around tend to fight for quite the opposite.

Those people are then caught off-guard when they use the phrase and find themselves labeled “racist.”

I just don’t see how the vilification of a specific phrasing of a common sentiment moves us forward. To me it feels like playing power games with words.

[1]: https://www.uua.org/beliefs/what-we-believe/principles/1st

For example, here's a case of a Democratic governor, running for president, getting caught by this:

https://www.cnn.com/2015/07/18/politics/martin-omalley-all-l...

And here is Hillary Clinton, falling into the same trap:

https://www.npr.org/sections/itsallpolitics/2015/06/24/41711...

At the time, women couldn't vote, Black people could be owned, and all people could be indentured servants, which significantly undermines the "Thomas Jefferson said 'All Lives Matter' almost 250 years ago" argument.

People wanted to say they don't like being left out of the message.

Nobody seriously opposed "black lives matter", but noticed that proponents of that phrase got vicious when faced with "all lives matter"; the latter is not a political slogan, but a litmus test for racism.