Sure that's the risk but fortunately that's not reality. If anything, the job opportunities are so numerous now because companies are no longer geographically restricting themselves, finding a job is going to be much easier in an already saturated (software development) market.
I've seen salaries of my peers getting remote jobs increase by 50% across the board, it's kind of insane right now.
Realistically, this has barriers in legal and tax implications. Employing someone in the EU has an entirely different legal and tax burden than employing someone in the US. For large companies, guess what: They were already doing this anyway. My last company had a dozen major tech sites around the world. But for small companies, like my current one, this is an effective barrier. And it even happens between states in the US, typically on a smaller scale.
What if this happened from the New York City headquarters? Or London, Frankfurt, Toronto, Sydney, Auckland, etc. Would you still post it? This comment feels at little bit discriminitory.