Problem if computer or internet connection breaks. The PO might return mail but a private mailbox service never will. Anonymity? There’s a record of everything somewhere for any person or agency willing to hack into, con into, legally seize, or buy! The Small Fish principle states there’s always larger fish to fry. Exactly what are you trying to prevent? Stalkers? Thieves? ID Theft? It’s wiser to spread yourself out across multiple connections that way, no one company has the whole sum of knowledge about you. One dishonest employee could have access to your entire life. Your question basically concerns the security of your personal info. The more difficult of a target you are, the more chance you’ll be skipped over for easier prey. Don’t put all your eggs in one basket. Scatter them, hide them, lock a few of them up, and don’t use the same dictionary word for all your passwords. Some day we’ll have implanted password chips, until then, hackers can decipher any dictionary word password in less than 24 hours.