basically what the sibling said. it's a good idea to isolate dev stages from prod by putting their respective resources in different accounts. it's also good to have separate accounts for different prod regions. people often don't do this because it sounds burdensome to have 2-3 dev accounts and 3+ prod accounts for each service. it is pretty painful using the out-of-the-box AWS web UI, since it forces you to log in and out of each account.

but the containers extension associates each account's SSO token with the respective container, so you can switch between them freely. you can also color-code and label the tabs from each container, which makes it harder to forget whether you're looking at dev or prod.

I am not the OP, but I believe he's referring to the ability to be logged in to different AWS accounts simultaneously. Without containers, logging in to AWS account B would invalidate the tabs where you're already logged in to account A.