It's the same concept as dogwhistling at its core. Like the terms "urban", or "big government", or "states' rights", or "law and order". Completely "neutral phrases" that are often used to communicate a hidden message with plausible deniability. I mean after all, who could disagree that "all lives matter" – it's obvious isn't it?

I don't really accept it's all that hard to be aware of the implications of the language you use to communicate. I suppose you might theoretically step on a "landmine", but I'll tell you what – I am virtually certain that nobody who has said "it's okay to be white" to their audience has accidentally stumbled upon a neutral phrase with good intentions.

These are terms used earnestly in neutral ways by academics, professionals and bureaucrats from all over the political spectrum. Does anyone seriously thing the NHTSA or some sociology professor is dog whistling when they use words like "urban environments" or "law and order"?

Yes, you can communicate a hidden message with them but you can communicate a hidden message with damn near any words in the english language if you want to.

So then someone whose politics favors authoritarianism and centralization will propose some federal power grab, opponents will make arguments favoring local control and the authoritarians will try to tar them with slavery and Jim Crow even if the subject is unrelated, e.g. whether the FDA should be overruling the states on whether or not to ban a thing in their state.

It's essentially an attempt to prevent anyone from taking the neutral position by making an accusation of guilt by association. Nazis are bad, Nazis built roads, therefore roads are bad.

It is quite dishonest to claim that this phrase is neutral and not a political slogan.

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.