This is a great way to frame it, and it is indeed how I approach composition as well. It sometimes helps to think of a piece as a solution – maybe the only solution – to a set of constraints.

Three limitations that I love in Pd off the top of my head:

1. The relatively small set of core objects really helps with programming ingenuity, and in fact has made me think through some things that have been helpful in other programming contexts. I love when someone throws down a "this can't be done in vanilla" challenge; I've learned lots from thinking, "OK, we'll see about that!"

2. The smallish set of objects also means that Pd is not a black box. It does mean sometimes that you have to know what you're doing, but in general it does not force you to think a specific way about what you're doing. This is not true in my experience with my students who use other programs excluding csound and SC, but including Max – they'll often as a group settle on one massive object or plugin that does 100 things in a really specific way (look at this badass object I found!) and all end up writing more or less the same piece due to the directions the design of the object pushed them in.

3. Its visual austerity is a huge help to me in thinking clearly about patching and dataflow. It's amazing how often a geometrically elegant solution turns out to be an elegant solution full stop.