If you use the cafe accounts and then your legit account(s), the log-ins will all be packed in the registry.blob file.. and valve gets the info and disables the account(s) that have been like used with an unregistered cafe shit.. I guess, not a pro at explaining.
.blob file has nothing to do with it check my sig for more info why accounts get disabled.
A obvious reason why they get disabled is if Steam idenfies you as Stealing accounts OR playing a game online or offline which the account hasnt paid for. For example awhile ago Ppatcher allowed you to play on VAC2 server a month later a flood of accounts got disabled. Which is why you use blank accounts or cafes.