Greece was a nightmare people don't really understand what was going on and the fact that they couldn't use an ATM, couldn't pay their bills, but at least that was a country wide issue.
When you get a similar situation but when one out of X people is left hanging in the wind because their bank has failed it would be considerably worse since there would not be a single unified emergency solution to cover them (in greece people stuck it out, there was even bartering, local stores had credit ledgers etc, GL getting credit from your local supermarket because your DB debit card won't work anymore), and when more banks start to fail because their investors and creditors lose faith and pull out (which is what happened to LB) it would make things worse and worse.