Earlier quoted context omitted.
These are classic symptoms of underpowered PIs. 99% of USB power supplies are not fit for a PI :(
So that raises the question: Why do they keep making Pis with USB power? One could argue that it's because USB power supplies are cheap and ubiquitous, but that's not really true if only 1% of power supplies are actually capable of properly powering a Pi. They could use a different power connector that doesn't cause this confusion, or they could design Pis to use less power and therefore work properly with more USB p…
A USB connector, at this point, is a PHY (like a serial DB-9 connector), not an inter-ecosystem compatibility promise (like a FireWire or SCSI port.) Lots of things use USB for lots of different incompatible use-cases. They just happen to share a connector.
But on the other hand, you can also think of it like a regular PSU: all motherboards connect to all PSUs, and there’s no way for a PSU and motherboard to communicate to “lock out” a mismatch. And a PSU will seem to work for a given configuration of motherboard+CPU+peripherals, until you drive that configuration hard enough to overdrive the PSU, and it shuts off.
The solution in both cases is the same: you overbuy on PSUs. A good high-wattage-rated power supply (whether a USB one or a desktop molex one) will power anything below that wattage requirement just fine. USB PSUs do negotiate power draw with the client device, so you can run a Pi off a big-brick laptop-class USB charger without damaging it.
And that’s mostly why Raspberry uses USB power, I think: if you already have a big beefy USB PSU from something else (as most early-market adopters do), you can use it to power your Pi for playing around, without having to buy the Pi its own PSU, if you’re not sure you want/need to set it up for its own standalone use-case.
(Also, the Pi will run just fine on a wimpy 5V1A iPhone charger if you don’t tax it very hard. Just like a cheap desktop PSU will power a gaming rig with a beefy GPU, if you never open a game. And most embedded use cases, e.g. PiHole, don’t tax the Pi very hard. So there’s a lot of cases where people get along just fine with the cheapest possible configuration, where forcing them to buy an actual power adapter would make things a lot more expensive for no gain.)
> or they could design Pis to use less power
You know that they stop selling old-model Pi’s, right? It’s not because they want to. It’s because those chips stop being manufactured upstream; and Raspberry doesn’t do enough volume to drive production of SoCs all on their own.
Raspberry is constrained by what parts they can put in a Pi that are both available and sufficient for the use-cases their customers have (e.g. driving monitors at native resolution.) Those chips have minimum power requirements. The power requirements never go down, because there’s no high-volume customer with exactly Raspberry’s use-case (where that use-case is “using process-shrinks to build a graphical desktop SoC of the same performance at ever-lower current draw, rather than achieving ever-higher performance at the same current draw.” An SoC process-shrink that is taken as-is with no commensurate re-layout for increased perf, is extremely rare in the industry. Not rare in microcontrollers, but an MCU can’t drive a desktop computer.)
You might suggest they undervolt the newer chips — and they do! — but there’s only so far you can undervolt a chip before it just stops functioning at all. (Especially an SoC, that contains DRAM that must get refreshed, IO controllers that must drive peripheral lines with to-spec line voltage, etc.)