@JeremyCherfas My email addresses are pivot points for other things so I wouldn’t want to lose them. That’s several. eBay, PayPal and Amazon are fairly critical. My bank too. Some online shopping sites (like Currys and Screwfix) let you buy without registering. Some (like Argos) make you register but don’t insist you save card details. So that helps.
There are some accounts that aren’t critical but where I’d hate to lose access to because of investment, reputation etc.