I think due to the exorbitant cost of upgrading internal laptop storage, 2.5" external hard drives still have a place at least for a little while longer. For use cases that require portability, a lot of storage, and aren't performance sensitive, such as backups on the go or bringing a large media library with you, there aren't really many better options at reasonable prices currently.

It is increasingly difficult to find laptops that even have a 2.5" bay. The drive for thinness makes it a tough sell, especially since the primary storage is always going to be a M.2. You basically only see them on aircraft carrier "gamer" laptops that are already huge because they need a massive cooling system for the graphics card.

If you're talking about upgrading old laptops where it only has a 2.5" bay that's even worse. Windows 10 and later absolutely hates running on 2.5" spinning drives. It can take literally 30+ minutes to log in due to the amount of thrashing it does.

I believe he's talking more about external 2.5" drives. Their low power usage means they can be run off a port with no need for an annoying wallwart. SSDs are definitely encroaching into this space but 2.5" HDD still have a cost advantage.

Shouldn't a USB-C port have enough power delivery for a 5.25" drive? Or do the external drive enclosure manufacturers not want to step up the 5v to 12v?

Assuming you mean 3.5" instead of 5.25" (as you wrote), no. Probably not.

USB-C is able to provide up to 3A of 5V, eg up to 15W. But that's not universal, and many devices are not capable of supplying that maximum.

Even if it were universal: 15W is a little bit less than what a fairly-normal 3.5" drive needs to get spinning, so there's not enough power available (no matter how it is sliced and diced with voltage conversion).

"But that's just existing drives! Certainly, they can produce a drive that spins up slow enough that it fits within USB-C's power constraints!"

And certainly, that can be done. But there's still more mass to accelerate in a 3.5" drive than in a 2.5" drive, and that acceleration will always require more power (Joules). This matters for portable devices (which often run on battery).

Even once spinning: All else being the same, it takes less power to keep a smaller platter spinning than it does for a larger platter. It also takes less power to accelerate a smaller head actuator than it does a larger head actuator.

"But what about USB-PD? My phone charges with dozens of Watts. Why can't a hard drive use this, too? What if we cast aside power efficiency and yeet this thing together?"

It absolutely can be done. Anyone is free to create USB-PD computer accessories. Some people may even be able to use them. But since USB-PD availability is anything but universal on host ports, and is even less-universally understood, that limits compatibility from "works everywhere" to "works sometimes" and the support costs (and negative reviews) will be through the roof -- unless it is very selectively marketed to niche players who know exactly what they're doing.

It doesn't even seem like it would be particularly challenging to create for someone with the right skillset. And yet, there appear to be zero consumer products which operate this way.

A ~6TB M2 SSD upgrade on a laptop is anything BUT cheap, even external ones. That's why these HDDs exist: For the data hoarders on a budget who also need some portability instead of leaving everything at home on a NAS.

You keep your existing 512/1024 SSD in your laptop for the "hot data" (OS, apps, frequently used work files), and get a 2.5 HDD for all the "warm/cold data" (steam library, photos, Nextcloud, backups, movies, etc). Storing all that type of data inside the laptop's SSD is kind of a waste of money at current SSD prices unless of course an 8TB NVME is not a huge expense for you, then by all means, but not everyone has that kind of cash lying around, hence why these 6TB 2.5 HDDs come in handy.