I have one of these accounts (it's a dictionary word), and I can confirm everything the author has said is true. I receive constant onboarding emails I can't opt out of, "so and so thinks you're cute" dating profile notifications, weekly account recovery notifications, all kinds of random crap that was meant for someone else but due to slight misspellings come to me, such as important contracts from lawyers, endless…
I get emails from middle schools, online shopping of course, but also emails for at least a couple Trump supporters (not trying to profile; simply getting Trump campaign's constant barrage of emails demanding more money; nothing from Joe's side yet)
What I find particularly annoying is when parents use this account to register for a kid's school alerts. All sort of important stuff like "Do not send your kid to school this week!" or "Where did your kid go?" and because the school itself is also not super savvy, there is nowhere for me to send a reply saying "You need to fix this!"