If you like me have too many domains for different projects, email accounts get a problem. With any domain comes the responsibility to allow people to get in contact with you. Often I use a webmaster@domain or info@domain email address to enable visitors to contact me.
But At $4 / month for an Amazon Work mail account and $5 / month for a Google suite user maintaining many email accounts gets pricey. Also, it is a hassle to monitor all the accounts.
Often you simply want to have emails forwarded to a single email account, where it is possible to set up filters, and allows you to check mail in a centralized place. For example, have email@example.com be forwarded to firstname.lastname@example.org which is my primary email account. With minimum set up.