You convey tone through word choice and sentence structure - trying to convey tone through casing or other means is unnecessary and often just jarring.

Like look at the sentence "it has felt to me like all threads of conversation have veered towards the extreme and indefensible." The casing actually conflicts with the tone of the sentence. It's not written like a casual text - if the sentence was "ppl talking about this are crazy" then sure, the casing would match the tone. But the stodgy sentence structure and use of more precise vocabulary like "veered" indicates that more effort has gone into this than the casing suggests.

Fair play if the author just wants to have a style like this. It's his prerogative to do so, just as anyone can choose to communicate exclusively in leetspeak, or use all caps everywhere, or write everything like script dialogue, whatever. Or if it's a tool to signal that he's part of an in-group with certain people who do the same, great. But he is sacrificing readability by ignoring conventions.