It is gone now.
Docker is a congregation of technologies held together with duct tape and glue.
Eg. permissions handling is completely different on Macs with Docker Desktop from the Linux dockerd stuff: on Macs, it automatically translates user ownership for any "mounted" local storage (like your code repository), whereas on Linux user IDs and host system permissions are preserved. Have some developers use Macs and others use Linux, and attempt to do proper permissions setup (otherwise known as "don't run as root"), and you are looking for some fun debugging sessions.
No, it's not. What a wild conclusion to reach from the example you gave.
The price of letting less experienced people "go crazy" in the repo
If a new project these days commits node_modules to git, it's likely a mistake, but for legacy projects started before 2017 it was the lesser of two evils.
Edit: spelling.
Prior to lock files (and potentially after, as checked-in files are beyond trivial to modify and review and that can be worthwhile) committing dependencies in some form was basically the only reasonable way to have reproducible builds, unless you wanted to build your own package manager / lock file implementation.
Which is what Yarn did.