It makes sense because you are unlikely to run production workloads at home.

So you don't really need a half a terabyte of RAM and a 220v power supply for the world's most expensive electric space heater.

Instead people are most often interested in developing infrastructure-as-code or testing deployment strategies or doing tests to see what happens when outages happen. Logging, metrics collecting, simulating network failure, simulating software attacks. etc.

In most of those cases having a number of smaller machines makes more sense then trying to emulate a small datacenter on a one or two big ones.

In practice I think most people end up with 2 or 3 'big machines' for times when they do need the Umph or want to have a big storage array for their "linux ISO collections". Then having a number of Pis or HP mini desktops in arrays is just for good fun.

If I want to simulate full blown workloads and benchmarking then I can just use AWS or Azure for that. A lot cheaper to lease verts for a evening or two, then buy big machines and leaving them idle 99.8% of the time.

So, now I am left with building another system and I need to decide form factor. Is this going to be headless or run a GUI of some kind with a monitor attached? Should I buy a big ole tower case or move to a 6u or 12u rack system. I want more VRAM and I need as much PCIe as possible. One thing for sure is that I don't want it to be Raspberry Pi based. I have two Pi4 collecting dust that were fun and impressive for what they are.

I saw these mini racks and wondered how they would work with an extended ATX board. Could these be useful as some kind of "open air" or mining type case where you simply bolt stuff on. Definitely going to investigate, so while the exact application of mini-racking pi's is not my jam, I am thankful that it was brought up.

On the other hand, I don't go to the trouble this guy goes to. I just have a cheap mini PC plugged into Ethernet sitting on top of my router.

There are also other Arm SBCs that are much faster (and more efficient) than a Pi, like the Orange Pi 5 Max. Many homelab-related apps run just as well if not better on that, just have to make sure to settle on a supported OS distro.

Or experiment with VLANs, firewalls, QOS, and related. Sure transcoding multiple 4k video streams is intensive, but there's plenty to be learned about performance, networking, configuration management, DNS, fallover, network storage, rolling upgrades, SSL certs, VPN endpoints, and 100 other network services that run easily on today's SBCs.

Plenty to be learned with a handful of cheap linux boxes and even a RPI5 or RK3588 is quite capable. Sure not state of the art today, but home lab != hyperscaler, but just might help get you are job at one.

At least in theory, a Pi cluster has better failure modes than a single machine even if it's less powerful overall. And yes, I'm currently running on an old laptop -- but it's all a bit ad-hoc and I really want something a bit more uniform, ideally with at least some of the affordances I'm enjoying when deploying stuff professionally.

I have an M1 Mini which is more powerful than any of these, but MacOS is not really suitable for tinkering and anything that's not Apple(TM).

Doing GPU/intensive type tasks is more purpose driven than a homelab. For this, you can get a NAS with dedicated GPU for transcoding if you wanted, etc.

The call for large amounts of compute/GPU makes a lot of sense, and there's a lot of ways to get there depending on what's needed, relative to the electricity bill you're OK with if it ends up idling a lot more than anticipated.

Adding a mac mini/studio for crunching certain things might be enough for a single person or household. Adding other demands or users beyond that could change it.

I'm familiar with racks and gear, and had way too much of it when I pulled out of datacenters and went more virtual and cloud. The nice thing now is a lot of that virtualization can come home with a bit of the data center (power backups, internet backups, etc)