To Welu, why would that be a put-down? Almost all aspects in writing can be broken down to different archetypes, tropes, and shorthand. You can't straight up outline the depth of a relationship in a short story without some underlying definitive relations, and siblings is a pretty easy one, seeing as a lot, I would dare to say MOST people have siblings, or are very familiar with people who do.
In my own writing, when I write siblings, which isn't that often, I find it's fun to play with different sibling dynamics. They're siblings, but that doesn't say anything on what their childhood was like. My relationship with my sister is different from my friend's because they grew up side by side, only one year apart while mine is six years my elder and she basically moved out the house when I was in my 'brat little brother' stage, so where my friend sees her sister as basically an equal I feel like I'm constantly fighting to have mine see me as anything other than than a shitty little kid whose life goal is to make her life hell.
Plays, even more than short stories, are fantastic ways to show those little slice-of-life snippets into family dynamics, and the way they put information out to the audience makes it a fantastic medium for slowly revealing what the sibling relationship is. What any relationship is, if we're getting technical, but sibling relationships allow for a longer backstory than say, a college dorm room situation. There's more possible strife, more years of sturm and drang to pull from.
