Why not tell them yourself? Passive aggression on a news feed won't improve the situation.

On the other hand, if the neighbors are burning wet wood, pine or otherwise Doing It Wrong maybe they would appreciate a friendly heads up.

Why not help them build a Dakota fire pit?

It's essentially just a big hole with an air intake tunnel, so that fires in the pit combust more completely, with a very significant reduction in smoke and particulates.

You probably can't do anything about them being ideologically inconsistent with respect to burned fuels as an energy source, but you can reduce their impact on yourself and your mutual neighbors.

A bonfire's smoke moves in the wind's direction. If they sit towards the bonfire with the wind in their backs, what's wrong with that? Although if the smoke goes toward your home I understand you anger.

Yeah, this seems not-terrible - most of the serious health concerns with fires are with wood stoves, where smoke either enters a house directly or leaves a chimney and settles back into it.

From the article up there I get the sense that wood fires inflict a lot of particulates even when you can't smell smoke, but open-air fires are still way safer (on this level) than in-home ones.

Prius (virtue signaling) vs. bonfire (actual behavior).

The idea that Priuses are only about virtue signaling is silly. For people who don't much care about power and handling, they're good cars that can be bought for a reasonable price and are cheap to run.