So in the context of copious dumb users plugging in anything that fits the socket, the data PIN likely prevented a lot of damage while at the same time enabled HP to rack in lots of money on replacement OEM proprietary PSUs. Indeed I have seen on many occasians clueless plebs at the street market selling 2nd-hand appliances and quickly trying barrels from a pile of tangled PSUs until one fits, then trying to include that with the device they are selling without looking at voltage or anything. It’s common and I’m sure lots of gear gets fried because the general population is just not smart enough.

I know how to match voltage, polarity, and current demands. And I got stung. Spent a lot of time disassembling a laptop, trying different RAM sticks, removing wifi cards and other components as I was baffled about what this fucking blicking LED means when it is not blinking in any way to convey an error code. Removed the CR2032 battery to reset the CMOS. Just got a steady non-stop blink, which the manual falsely states means it’s in sleep mode. So I was ready to conclude that the laptop was trapped in sleep mode and irreparable.

Whether it is a good design to protect from incorrect PSUs (despite that the obscure barrel connector is probably only 19.5v systems anyway), most certainly it’s a crappy design to not inform users. To fail to assign an error code. Sure, it says in the manual something like “use only approved HP power adapters” – something /smart/ consumers do not take seriously because they know that shit is a branding hussle. The data pin should not be a secret that is concealed from both the user guide and the maintenance and service guide (which HP says is not for end users… yet they still withhold the info from service people).