If you use aliases for all services, it makes it slightly harder to automate trying one leaked email on another site, since the hacker needs to add the new alias on the other service.
No one is going through of all these credentials manually, so any extra obscurity can actually bring you security in a pinch. Although if you have different passwords this shouldn’t matter much…
The GP earning 6 figures for prescribing boomer cunts opioids is clearly in the same social class as the construction worker whose life expectancy is below the retirement age.