A Raspberry Pi (any versions, and their friends in the marketplace) is not a like a PC. It's a got a little ARM SoC. It's a lot smaller than your NUC -- it can fit into a normal pants pocket. It has easily-swapped storage, making brain transplants trivial. It includes weird interfaces, like for LCD screens and cameras, and also some GPIO that is included just for tinkering with and integrating into other projects.
It can do PC stuff -- of course it can. It has USB and HDMI ports (and Ethernet and Wifi), much as a modern PC might. It can run Linux (and a whole desktop OS) just as a PC can.
But it can also do other stuff that PCs don't generally do, and that PCs (examples like the awesome GeekPort on the BeBox[1] notwithstanding) have never generally done.
Your NUC was sold as a complete system (including an absolutely-required "esoteric charger") that can be unboxed, powered on, and immediately put to work.
A Raspberry Pi is sold as a bare board that -- by itself -- can't actually accomplish anything at all, just as a common PC motherboard also cannot accomplish anything by itself.
They're very different things, with potential use-cases that only somewhat overlap.
Why this is still an issue of contention after very nearly a dozen years of Raspberry Pi existence boggles the mind. I mean: Some people enjoy dining out (and may not even know how to cook), and some others grow their own food (and thus participate in every stage of its production and consumption by necessity).
Neither set of people are inherently wrong for choosing to do things their own way. Even if one set can't can't understand why the other set does things so differently, both are still perfectly OK.
If a person wants a prebuilt PC to do PC stuff with, then they should absolutely get a prebuilt PC (new with warranty, old, janky closet laptop, whatever) and do PC stuff with it. If a person wants a computer that can be (must be) tinkered with in a very hands-on way, then perhaps a learning- and tinkering-oriented SBC like a Raspberry Pi (new, old, 3, 4, 5, zero, Craigslist score, whatever) might be a better option.
For my own part: I own some PCs that I do PC things with. I also own some Raspberry Pis that I do more-hackish things with.
My Home Assistant rig runs in a VM on a (very cheap, used) small Lenovo M600 box, because I felt that this was the best way for me to accomplish my goal at the time. My usage of HA doesn't need any special IO, and I enjoy using VMs. It sits there and just works.
My DIY energy monitoring rig runs on a Raspberry Pi 3, because I felt that this was the best way to accomplish that goal at that time. The system I chose absolutely requires the Raspberry Pi's GPIO, and conglomerates as a very small contraption that is easy to co-locate near the circuit breaker panel. It sits there and just works.
I'm very pleased with these purchases. 10/10, they suit my own proclivities just fine. (If they didn't, then I'd like to think that I would have chosen differently.)
It's OK to have more than one kind of product in a marketplace.