[MillironX]

Table stakes is a poker term meaning the absolute minimum amount you are allowed to bet. So the title translates to "In S3, simplicity is the bare minimum" or "In S3, simplicity is so important that if we didn't have it, we might as well not even have S3."

[MatthewCampbell]

It's a risky idiom in general because it's often used to prevent debate. "Every existing product has feature X, so feature X is table stakes." "Why are we testing whether we really need this feature, it's table stakes!" My observation has been that "table stakes" features are often the best ones to reject. (Not so in the case of this title, though)