What I'm saying is if you use the same password for everything, that makes it more likely they can get the gmail password.
Take, for example, the reddit password leak. A clever attacker can probably guess my email from my username. If I had used my gmail password for my reddit password, now they have access to everything. But, since I don't cross contaminate my password like that, I didn't risk my gmail account.
That seems backwards. The problem isn't your gmail password getting leaked, but some other site leaking your password. If that site also has a clue about your email address, now they have access to your email, since you made them the same password.