@FediTips @kate Tested this out on my aunt-in-law.
She got two sentences far before she gave up with a condescending handwave motion, giggling to herself that "oh honey, this already sounds way too complicated, you lost me, you know I'm too old for this". She went on to prepare some tea.
Apparently the phrase "join Mastodon and the Fediverse" did the job. She doesn't want to sign up to something that 'comes with some secondary contract to something else, and who knows when you can cancel that or if I even need it'. She reiterated that she doesn't 'need two social medias' and that it can't be easy if it's two things in one. 'Facebook is just one app and that's perfectly fine', after all.
She apparently had made bad experiences with a TV sat salesman 30 years ago who sold her a combo contract that included not only the TV connection but also an internet connection she didn't need, and she felt cheated and deceived.
Of course she didn't read the Fediverse explanation link because she doesn't click links. 'If it doesn't fit into the same page, it's too complicated anyway.'
When prompted to click regardless, she reluctantly did, and upon spotting multiple paragraphs worth of text and more links, she immediately decided it'd be too long and complicated anyway. She condescendingly said it's very nice of me to try and help her but that she's too old for nerdy hobbies.
She's back on Facebook now, complaining about people she doesn't know putting photos on her timeline, and about all the right-wing fake news she's correctly identifying as such (thank god).