Speaking for myself, the "blast radius" of my email address is some 600+ accounts... (just looking in my password manager). The chances of me sitting down and closing every single one are non-existent. Many won't even have the luxury of having diligently tracked their login accounts in a password manager either.

Just having a family, kids, bills, schools, jobs, credit cards, banks, investments, insurance, shopping etc etc - the number of accounts many of us pick up can easily get into the hundreds.