That's a great example of "if you're not paying for the product, you are the product". Reddit is transparently associating changes in the privacy policy with Reddit Pro, that calls itself a suite of tools "for businesses to also establish and grow a meaningful organic presence on Reddit" (translation: so corporations can astroturf the shit out of local communities).
That saying (I wouldn't call it a "rule") applies mostly to for-profit products and services; like, if they're doing it for the money, and you aren't giving them money directly, you're doing it indirectly, and you should find how. Lemmy instances on the other hand are [mostly? all?] non-profit, it's just a bunch of users trying to nurture communities to talk about stuff that they enjoy.