I think sales touches on it, but still the persona you adopt is a "sales representative". You are selling a product, your insincerity is locked to the product, with a few curated pithy anecdotes to flesh out the role. It's closer to acting. You're using charisma to make the sale, but you still take your hat off at the end of the day. You interact with a few individuals over the course of the day, and likely never see them again. If you do have an ongoing relationship with clients, it's one-on-one and segregated. And you can choose how much you want to rely on a persona, you can do sales from a position of relative sincerity if you actually believe in the product.

With streamers, their identity is the product. They aren't using charisma to sell cars or vacuum cleaners or medical equipment, they are selling their personality. A sales representative doesn't have to change their being when market research demands a change in product. If a streamer wants to change their product, they have to change themselves, or at least their persistent persona. Because it isn't one-on-one and segregated, they have to be their persona all the time for thousands of anonymous commenters at once. It's fundamentally existential. You can't do it another way, it's endemic to the industry

Steaming may be soul-sucking in unique ways

Yes, that was the entire claim. No one said other jobs don't suck out your soul. The only claims were that there is a way which is unique to streaming, and that it's basically universal in the industry. No one's trying to negate the fact that other jobs suck.