Because the point of cache is to save time, not waste it. Like most naïve delays in response to timing attacks, that also doesn’t solve the tracking problem – i

Because the point of cache is to save time, not waste it. Like most naïve delays in response to timing attacks, that also doesn’t solve the tracking problem – if there’s any detectable difference (consider a cross-site tracking server that serves the content with a controllable delay) under any circumstances (consider network and disk load and availability), the mitigation is defeated. Sites don’t share that many resources byte-for-byte anyway. The current solution is fine.