Present or Past in “They said they are/were breaking up”

Question

This single includes two killer songs recording in Portland, OR while embarking on their first (and, sadly, last) US tour, that are the perfect follow up to a their self-titled LP we released last year .The band just completed a European tour and announced that they are breaking up. And while this is unfortunate, we're happy to have had the opportunity to bring the majority of their catalog to the US.

I know that past simple can sometimes go with "just" as it is the case in this sentence. But why did the author choose past simple instead of present perfect? Does it change the meaning of it ? And why is it not written:

The band just completed a European tour and announced that they were breaking up

because all actions belong to the past?

Answer 1

[W]hy is it not written:

The band just completed a European tour and announced that they were breaking up

because all actions belong to the past?

It's not clear that all the actions do belong in the past. Remember, the present progressive, despite its name, can have a future meaning:

We're going to the movies tonight.

If the had announced their breakup in 1997, you should definitely say, were breaking up. But since the announcement is still recent (at the time of writing), the actual breakup could still be in progress, or planned for the near future, and are breaking up is appropriate.

Answer 2

The sentence is correct grammatically whether you say "they are breaking up" or "they were breaking up".

In fact, the sentence is indirect speech.

If there's a past-tense verb (said, told, announced, etc.) in the reporting clause, we usually change the tense in the reported clause when we form indirect speech. However, if the statement is still up to date, we have the choice. We can keep the tense as it is, or we can change it. Let's look at the following sentence:

Sarah said, "She is going to New York on Sunday".

As her statement is still up to date; it's true she will go, you can change direct speech into indirect speech as follows:

Sarah said that she was going to New York on Sunday.

Sarah said that she is going to New York on Sunday.

Now let's form the OP's sentence in direct and indirect speech.

The band announced, "They are breaking up". (direct speech)

As it's still true that they will break up, you have the choice of leaving the tense the same, or changing it into the past.

The band announced that they are breaking up/they were breaking up.

As the OP has said, it's also correct to say "The band has just completed a European tour and announced that they are breaking up".