AI struggles to make a complete, composite product. This is the limit on game creation as it is anyway, not number of assets available to steal/download/buy. There are thousands of options for near-complete games out there that can be easily customized further with the millions of art assets out there as it is.

Even then, Steam isn't completely without moderation. It's been possible to automate the creation of asset flips for a while (and we've seen it done plenty of mobile), but Steam makes some effort to remove the lowest quality games and make it ineffective to publish low-quality shovelware. AI is still quite a ways off from being even remotely faster or more effective than just buying a template and filling in the resources with cheap or free assets.