Hollinger's system is not without flaws, but the reason nothing else has gained traction is that there really isn't any better metric that's reasonably standardized.
Well, there is. Wins Produced. It is a far better metric in that it more accurately reflects performance (for example, if you perform retroactive analysis, every championship team over the past X years lead the league in Wins Produced, which isn't the case for PER. This automatically makes WP a more accurate measure), and is standardized. In fact, you could argue it is MORE standardized than PER, because it controls for minutes played, which PER does not.
The only reason better statistical measures haven't caught on is because most fans are unwilling to trust them. They prefer to use the "eye" test, which is incredibly inconsistent and unreliable. PER tends to match the "eye" test more than other measures, because it overvalues scoring and offensive output, which is subjectively more eye-grabbing and memorable. So even though there ARE better statistical measures, people don't trust them because they don't automatically reflect their pre-conceptions of who is good and who isn't.
There is nothing wrong with the stats. The problem is people don't LIKE them.
EDIT: Heck, you can see that on this forum. Almost anytime stats are brought up, they are dismissed by a dozen people saying "Well, stats aren't everything!!" I am not saying stats can explain everything. They can't. But stats, unlike our subjective opinions, are predictable, reliable, and consistent.