In the following sentence, why is the present continuous used?

"The two of them are always getting into fights."
And what is the difference between the sentence above and the sentence below, with the present simple:
"The two of them always get into fights."
I have not been satisfied by the explanations given in course books and I'm trying to find a clear, succinct way of explaining the distinction to students. I'm having a hard time seeing any difference myself (as a native speaker).
Look at these two sentences:

1.He always buys me lovely presents. (Present tense)

2. He is always buying me lovely presents. (Present Continuous)

Can you see that in (1), the emphasis is that the present he gives me is 'always lovely' - this might be on my birthday, and at Christmas.
In (2), the emphasis is on the frequency, where 'always' now has the connotation of buying a present for me at the drop of a hat, no special occasion.

So -
"The two of them always get into fights." - emphasizes that when they meet/interact, it becomes a fight (with always=on all occasions, if and when they occur). (This might be the pattern over many years, when they have got together at the extended family Christmas gathering - that is, once a year but a pattern established over many years experience of these gatherings.)

compare:
"The two of them are always getting into fights." - this emphasizes the frequency with which this happens, and always=repeatedly