Linux

Seriously? Number 1-4 are just outright stupid claims, or misguided explanations at best. I especially laughed at the "system being in read-only mode" stupidity. WTF do you think EVERY SINGLE Unix-like system has configured, world writable everything?

The important parts of the filesystem are mounted read-only so you'd have to explicitly reboot and mount as read-write. That's a lot different than marking individual files or folders as read-only which is what you're referring to.

The atomic updates but is also pretty stupid, since that's literally just a process difference,

Yes and no. To get the same behavior without an immutable OS you'd need to take a snapshot before every update and update every package on the system every time and install no additional packages.

and unless you're running a stock base image (which almost nobody generally is), then you're not getting full atomic updates globally on your system, and certainly claiming they have no problems is dumb as hell. They then try and point out that NOT being able to update a single application is some sort of benefit, which, hey...maybe that's subjective, but it's outright just a dumb claim.

I'm guessing you mean "stock" as in never installing anything additional. If using the base packaging system is your jam then absolutely you shouldn't use an immutable OS. There are plenty of alternatives to doing a apt install and that's what you're encouraged to do because those options don't usually involve writing to important system dirs.

Lastly, there's a claim in there seems to sound something like it's normally a battlefield amongst running applications on a non-immutable system, and that somehow there is problematic interaction between programs which is, again, false and ignorant.

I can't say I've ever run into two packages that, in effect, conflicted with each other, but I've absolutely seen packages conflict during installation where I was forced to look for an alternative package without a conflict or complie from source.

Writing "because you're forced to use containers" doesn't ring like a feature, so of course they're going to phrase it the other way.

Saying, "Look at what you can't do!" is usually not a good idea but depending on your priorities and skill level it's really about taking riskier options off the table. Yes, some things are more challenging using containers but the likelihood of a container making your machine unbootable is practically zero. I've run and administered Linux machines (personally) for over 20 years and not working about base packages has frankly been a load off my mind. And because I'm doing more things in containers I'm coming up with solutions I can easily port to any machine.

I would never say immutables are better than standard distros but I don't think it's fair to say they don't provide any advantages or that you can get the same benefits simply by changing your habits.