Re-thinking about this, is correct what @hobnob says. I was stating something that is true for PHPUnit tests, but with Behat we don't need it as we always work on a scenario level. We don't need to instantiate the db at a feature or suite level as happens in PHPUnit with `setupBeforeClass` and `teardownAfterClass` hooks.
The difference is all about performances. With PHPUnit - if you don't need a DB explicitly - is pointless to create and delete a DB at every test. So it's ok to create it once at the beginning of the suite and then just refresh it where you actually need it. 
The same thing is true for Behat, but in behat there is no access to the kernel before scenarios as that is the point in the behat events lifecycle where the kernel is injected, so there is no way - unless we write a solution by our own -  to access the configuration and the kernel before the first scenario.

Therefore is ok to remove those two tags.