Well, my inbox has tens of thousands of emails. Every January or so, I put last year's messages into an archive for that year. When I look for something, I use the search feature.
Works like a charm for over a decade now. (But I don't get aneurysms when other people handle it differently.)
I filter emails like the article suggests, just a bit more detail.
Newsletter, notification, and work are my main tags.
Then I have some specials like tax office, banks, crypto, academia, etc.
Most of it gets archived right when it arrives.
At bussy times, I have like 20 mails in my inbox for 1-2 days, but most of the time my inbox is empty or had under 5 mails.
I also treat these mails as tasks. Everything in my inbox needs to be tended to, and when it's done I send a reply or archive it.
Works like a charm for over a decade now.