Honestly in rare situations that a device like that needs to be accessible from the wild Internet I think it’d be mad to expose it directly, especially if it’s not manageable as you suggest. At the very least, I’d be leaning on a reverse proxy.

I don’t know why but I thought they were some special inaccessible computers.

It’s their marketing. Marketing, marketing, bullshit and marketing. Macs get viruses, Macs have vulnerabilities, Macs crash. Doesn’t matter how much their indoctrinated fans might claim otherwise, Macs are just weird PCs. In that context, their refusal to allow their owners to control them is all the more jarring and makes owning the older models like you mentioned all the more sensible.