The benefit of "The service is now ready. To check the service's status, ..."

Is when someone needs to amend this sentence later, e.g. inserting another point:

"The service is now ready. This means you can query the health endpoint. To check the service's status, ..."

It makes the writing less likely to become ambiguous.

Most documents I see in work will constantly have sentences added/removed as things change.

Many 'rules' including this one can be broken if you know the tradeoffs and can make the case-by-case choices correctly. But that was a poor example for motivating a behaviour.