"Why exactly is that an issue?"
It's not an "issue," it's a problem. It you had bothered to read the entire post, you would have noted this:
"...[M]ore and more apps insist on being able to communicate with the Google Store to confirm their authenticity, else they won't work."
I read the whole post. That’s not a problem. Not if your priority is to cut off Google.
The apps don’t matter.