Alright I'll bite.

As you move down the wealth ladder you eventually reach a point at which there is a culture change. There are significant differences in the culture of the average middle-income anglo with guilt about their privilege compared to the people who are really, genuinely struggling. Once you cross a certain threshold, I'll call it the poverty threshold for the sake of this reply but it's not really a strict line but more of a broadly intersecting spectrum where there are many people who can blend into both groups, you reach a behavioural change point. This behavioural change, both in speech and in attitudes, is generally driven by those of us below a certain income level genuinely not giving a single fuck about how someone speaks but rather what they are saying.

Take for example my home of Liverpool. If I go down the council flats I'll find myself hundreds of people who will speak in ways that the middle-income liberals of america would find abhorrent. They will cuss you for a minor thing that makes it seem like you just killed their dog. This is normalised culture for them, and among their peers it is perfectly fine behaviour - but to the sheltered middle income person who sees it as an overreaction? It's shocking, and they don't like it.

This trend occurs towards the lower income groups because frankly their is less and less incentive to ruin relationships with people over social policing. Far more is put up with and accepted because everyone's got it rough and nobody's interested in making someone's life harder by getting overly emotional about a few swearsies.

I fit into one of the blending people, seamlessly transitioning between the two and speaking both ways. I grew up in squats, but I also got a very fortunate break that led to me getting an education in what many would regard as the ruling class side of our education system, which is split between schools for the workers vs schools for the bourgeoisie.

Anyway. The point is that the tone policing has the effect of shutting out these people from participation. The reason you don't see the majority of these people in participation online isn't because they don't have access, it's because they've had the experience of getting banned everywhere for not speaking like a cultured middle income liberal, and they've frankly got bigger priorities in their lives than learning how to speak like the people they fucking despise.

It is classism because it explicitly shuts out this class of people from participation. Almost everywhere online the tone policing functions as a tool of class discrimination that bends internet culture towards privileged middle-income groups over the poor. It's not explicitly intended to do this, but it is the outcome of it. Much like for example having a "no hoodies" rule in a shop doesn't function to keep out middle-income people but keeps out the "chavs", if you'll forgive my use of a classist slur for effect.

You wanna get aggressive and go at it? Go ahead. Do it. How something is expressed is not important compared to what is actually being said. The issue with this form of classism is that a section of society goes completely unrepresented online because of it, people whose politics almost always align with my own socialist views once they're well educated in what their interests are.