There are plenty of necessary sites that just don't let you have multiple accounts for management. I can think of a few but there are tons more - ebay and PayPal are the first two that come to mind. You also get into "concurrent licensing" issues - lots of companies make you pay for each "person" you have tied to the account (like an infrequently used fax number). Account sharing is a necessary evil - but the other comments you mentioned are dead on.