I think this might just be inherent to the currently deployed LLM architecture. If the training process works at all, any model will come out of it with some (default) voice that it'll apply everywhere.
Human voices are not like that, both because one copywriter does not write a significant fraction of all texts in the world and because unlike LLMs they remember all of their own prior writing, which gives them an opportunity to get tired of their old tropes.
Why do they specifically push for this voice? Because it is effective. This is "headline voice", the voice that gets people to endlessly click on Youtube clickbait and garbage articles. Most of the population gets a dopamine hit from this style of writing, making it legitimately addicting to them. Those who recognize it for what it is and find it insufferably grating are in a tiny, tiny minority.
The tiny minorities are the people who are too dumb to notice, and on the other end, the people who can still sift through robot-made clickbait the same way they were wading through human-made clickbait before.
The stylistic elements on their own wouldn't raise an eyebrow if they appeared rarely among many other stylistic devices in order to enhance drama, suspense or emphasis, but within a single completion, Claude will sometimes implement just these two several times to express the most banal things. It ends up looking like a caricature of the worst pre-LLM Medium and LinkedIn garbage.
Read some early pre-mass-adoption LLM papers by the key scientists and researchers. The style is very similar...