> this is what I don't get. Why would anyone in their right mind use a language ecosystem where each major version upgrade breaks their code?

Great so let's just leave all of the legacy terribleness in it. Let's not address all the quirks and horribleness that sounded like a good idea at the time. Let's not let the language evolve.

For the longest PHP was really great with backwards compatibility, refused to address issues in the name of backwards compatibility. So it became the butt of the jokes it is today.

As you can imagine, I'm on the other end. Providing backwards compatibility is kept for a relatively long time, I don't think it's unreasonable to break changes with a good system (i.e. major version upgrades). In such cases, I welcome it.