As an individual you don't care as long as you aren't in that 1%, but as a customer-obsessed service owner I absolutely care if a bad experience is happening 10

As an individual you don't care as long as you aren't in that 1%, but as a customer-obsessed service owner I absolutely care if a bad experience is happening 100k times per day. If you're operating at internet scale you need to look at both percentiles and absolute numbers to assess customer impact. Also keep in mind how percentiles compound when you have more than one service involved in serving a customer request. For example, let's say it takes 5 internal requests to serve an external customer request and each of those services measures latency SLAs at the 99th percentile. The customer request may only finish inside the SLA 95% of the time (99%^5)