Once again Apple is showing how to do things stupidly. They won't allow you to boot from an external HDD/SSD if the internal one fails. On top of that they make it extremely difficult to replace the internal disk on your own. Carbon Copy Cloner has been my number one program all these years, but I think that Apple is pushing us loyal and technical competent people away. They just want "simple" users.

They want you to take the device to the dealership.

Perhaps, but there’s a security angle to this as well. iBoot is stored on the internal SSD. If you want to bypass the internal SSD entirely for the boot process, you must now trust that any external drives plugged in have non-evil versions of iBoot installed, as the Mac will now have to go to every external device and say “can you tell me how to boot?”. If the internal drive is the only place to get iBoot it makes the security strategy way easier (since the only way to write to it is via DFU connected to Apple Configurator). We know only people with the keys can modify the internal drive, so we don’t have to keep certificates or something else around to verify it is trustworthy. Who knows where the external drive’s copy of iBoot is from.

You could make it so there’s a break glass copy of iBoot on another chip, but then that’s something they can’t update if there’s a bug.

The SSDs of 2015-2017 macbooks start failing and they are soldered on the board. I have a 12" that I can only boot from external now otherwise the device would be dead. With the M1 models you don't even have the chance to do this. Apple won't even change the failed ssds they will sell you a new logic board for the prize of a new machine. It's infuriating and the only reason I won't buy a machine until they make user replaceable storage the norm again.

I noticed that AppleCare, which use to be a one-time purchase of 3-year coverage, is now offered as an annual purchase that can be renewed indefinitely. Presumably this means that, as long as I pay my $150 rent, they will replace my logic board, with its failed SSD, for free?

Maybe a deductible, but otherwise I have to assume yeah. That’s not cheap though.

I suspect they began soldering it because the cable connecting the disk drive had a lot of problems in older MacBooks. Soldering may have been an easy fix for that.

I hate the soldering, too. I'm just offering an explanation that may make some sense given the context.

What cable? As far as I can recall, everything not directly soldered since about 2013 was ssd mounted to motherboard using either M.2 or a similar proprietary connector. I suspect it was Cook-ish financial engineering and that trademark Apple hubris (that they finally got over to re-add ports in the most recent MBP).

Here's an older thread on the cable: https://discussions.apple.com/thread/7794520

This was pre-2013. So perhaps the proprietary connector was a reaction to the cable?

I like your Ockham razor reasoning, but given the history of this company, it would be very difficult to defend this claim. Soldering the SSD and memory made the device unupgradeable (in contrast to pre-2013 models where I have currently have 2x2TB!).

pcie and nvme ssds use ports that are similar to ram slots there is no more cable involved.

And 2.5 inch drives can and often do have ports directly mounted on the laptop motherboard. If you don't want to use a cable, then you simply don't use a cable. Nothing else changes.

It's less the cable than the connector, so, similar trouble with nvme ports (and ram slots, for that matter). I've barely had exposure to supporting laptop hardware, and have seen "thing shimmied loose" or "contact corroded" as the root cause of problems more than once.

680 Euros quoted from the apple store in berlin for a 2012 macbook.

I don't think it would turn out a plus if I fly over to get it serviced.