You know, behind these on-the-surface feel-good / oh-that's-cool stories is generally a less positive tale of deferred maintenance and poor choices by AA (and other airlines) that leads to this kind of rescue flight being necessary.
The article was from 2016, and the question you want to be asking is, "how often should a 2 year old 787 be having engine issues requiring unplanned diversion?" and is AA's maintenance regime causing them to encounter these situations more than is expected?
What you will generally find is that because of labor costs in the US, and the thin maintenance margins that our carriers are incentivized to follow (partly also because penalties for stranding passengers is quite low), these kinds of diversions are more frequent than other airlines operating better-maintained long-haul routes.
Things are always breaking on airplanes. How much proactive maintenance is conducted is up to the airline, and determines how much builds up before 1 out of many issues on the minimum equipment list rises enough to ground the aircraft. It's quite an active decision for an airline, actually. In this case, AA maintenance probably made a decision (under all the other constraints they face) to fly the 787 to Shanghai (where they don't have a full maintenance depot) with some marginally performing or slightly-overdue-for-recommended-replacement engine part. And then on the return the strategy backfired.
Consider that when you wonder, "is it just me, or why does airline X seem to have so many more delays and aircraft swaps than others?"