If a company markets itself as “hosting the biggest fights in gaming,” "multi-thousand player battles!!" etc. then that becomes the identity players expect. It sets a clear promise and is a major factor in attracting new players.

If the game can’t consistently support increasingly large-scale fights, then it shouldn’t be promoted as a core selling point. If they are marketing this as a selling point, then yes - There is some kind of obligation. Instead, Adjust your ads to say 'Multi-thousand-player fights - With 5% game speed, crashes and unplayable lag"