Take this for what it is - I'm a software developeer who works in the cloud, not a cloud expert.
The abstraction behind AZs is what every AZ counts for at least 1 data centre. So for every region there is at least 2 AZs, and every AZ means at least 1 data centre (or 5 in your link).
This just means it's harder to take out a whole region by destroying individual data cetnres. Since most regions consist of 2-5 AZ, and AZs consist of 5+ data centres, that means destroying dozens of data centres.
The abstraction behind AZs is what every AZ counts for at least 1 data centre. So for every region there is at least 2 AZs, and every AZ means at least 1 data centre (or 5 in your link).
This just means it's harder to take out a whole region by destroying individual data cetnres. Since most regions consist of 2-5 AZ, and AZs consist of 5+ data centres, that means destroying dozens of data centres.