No, they’re not doing it from a functional standpoint.
Like, if you were playing a blues in A, they would call that one D7(9) and then they would also call it E7(9) for the V chord.
That’s just the way they do it? It doesn’t make any sense to me.
Especially because in a sight reading situation, too much information is often worse than not enough information.
They are far from the only offenders though. In general, there are a lot of things that are permissible or standard for publication or in academic contexts that are totally different than what’s preferred in a gigging context.
In a gigging context, the guitarist is part of the rhythm section (along with the bassist and the drummer and the keyboard player). And the most important thing in the chart is to make the form really obvious.
So you want there to be four measures in each system so that you can see where the form rhymes with itself.
And you break from that rule of four bars per system when it makes the form clearer, because you want the whole chart to be glance-able.
Another thing that’s really changed the way charts are written is the ubiquity of iPads for gigging musicians.
No one uses paper charts on a stand anymore if they can avoid it. When it was two or three pages on a stand that were taped together, you could have repeats that wrap or span more than one page.
But it’s a faux pas to do that on an iPad. It’s better to avoid repeats… with the exception of very specific vamps, like “this is an open solo” or “we vamp on this thing while the singer talks and then we play these hits.”
I mention these things only because you won’t find them in a textbook but you will very much find them out in the “real world.”