We live in a class society.

the esteemed readers of the New York Times

The "middle class" historically are bourgeois. They're the "middle" class between the peasantry and the nobility. Since the bourgeoisie supplanted the nobility as the global ruling class, "middle class" has mostly just turned into vague self-identifier of relative income among liberals. American minimum wage workers and millionaires both broadly believe they're "middle class" while everyone with less accumulated wealth is the deserving poor and anyone with more is the decadent cosmopolitan elite. Neither will consider what that implies about the relative wealth and income of most Americans compared to the majority of the world, because of course, only imperial citizens are "middle class" (free, democratic, good, etc.) and everyone else in the world must either be primitive savages who choose to live in squalor, or brainwashed subhuman bug-people whose collectivist totalitarianism is threatening America's ability to produce this "middle class" lifestyle for an increasingly small minority of humanity.

Citations Needed has a great episode about the phrase "middle-class". "It’s a capitalist carrot hovering over our heads telling us such things are possible if we Only Work Harder. More than anything, it's a way for politicians to gesture towards populism without the messiness of mentioning––much less centering––the poor and poverty." https://citationsneeded.libsyn.com/episode-91-its-time-to-retire-the-term-middle-class

It honestly depends on how you want to define it and under what framework. In Marxism the definition of class depends on the relationship to the means of production. Obviously using the Marxist framework is the most accurate to describe what's actually happening and as Marxists we should use those definitions and try to inform people as best we can that proletariat and bourgeoisie are the two main and oppositional classes (primary contradiction) in capitalism. But like Mardoniush pointed out there still are other classes since the relationship to the means of production can be more complicated than just straight ownership vs labor despite the antagonism of those two classes being the primary contradiction.

Still, none of those are a "middle class" and you are completely right about how one of the big reasons that term gets heavily used is so the parts of the proletariat that are not impoverished can feel elevated above those who are. But that right there means there is a material difference between certain subsets of the proletariat that gets called "middle class" and "lower class." There is a large subset that historically in the US was generally well off (comparatively) to the subset that lives in poverty conditions, and it is true that the former subset is shrinking while the latter subset is growing (along with the intensity of the contradictions). It is not wrong to point this out, and "middle class" is definitely not meaningless when used this way, it's just that using the word "class" to describe this phenomenon is deliberately muddying the waters and it's not using the term according to a Marxist framework. Don't mistake that to mean that what the OP article is saying is untrue or isn't happening, because it most definitely is happening! It's just bad semantics.

There are more classes (there are still a few owner-operated farms, which technically count as Yeomanry, and the PB is a different class to the HB), Proles and Bougies are just the main ones.

I think the overwhelming reason was less an issue of taxes, and more an issue of Britain pressuring the ending of slavery which was the entire basis of the colonies economy. Britain levying taxes unilaterally was unpopular for 2 major reasons, they did not get any input from the colonies, and the money was being raised to pay debts related to the 7 years war, something the colonists felt they had no responsibility to pay.

The taxation was something easily sold to everybody, but the true concern of the ruling class was Slavery.

The 1772 Somerset Case ruling is a good place to start if anyone would like to read more about this.

Edit: to clarify, it’s not as black and white as I make it seem. But slavery was the major function uniting the south in the north’s bid for independence.

Yeah, but you don’t need a democracy just because you had a revolution over taxes. It was a democracy by and for the bourgeoisie out of necessity, meant to handle internal class conflict for a class that was far from nonhierarchical, but also much more distributed than the strict pyramid structure of the monarchy. The settlers importing and enslaving a bespoke proletariat resulted in a class fluidity that made it necessary to establish governance that would accommodate that fluidity. Specifically, of the ruling class being based on capital ownership as well as race and sex.

it's like they're close enough to taste it but not strong enough to follow through.