Why wouldn't they just skip the journals and publish the papers themselves? Sharing the research is the important part unless these are academics who are trying to get tenure, grants or such.
Moreso if your current employer is a stealth AI startup which hasn't yet produced much notable.
It also can encourage employees to work for fewer wages... 'If you do great work you can publish and then get a $$$$$$ job offer at OpenAI, or you can stay here and get equity in a fast growing startup. If however your work doesn't do well, you walk away from a bankrupt startup with worthless shares and minimum wage'
To answer your question, sharing the research isn't the important part. These are researchers in the private sector, in a highly competitive field. Arguably, doing the research isn't the important part either. The important part is making money, and the research is a means to that end. Publishing the research doesn't further that goal, and, according to GP, it's so difficult that it may not be worthwhile trying.