I mean, it's a pretty simple scenario that unfortunately happens. Maybe it makes the police complicit, and maybe a guy had a buddy who had a buddy. But more likely it makes them look lazy or under-resourced. It's not an easy case to investigate or close, and in reality police forces are often forced to deprioritize some matters in favor of others where they can prevent and prosecute more frequently and easily. They apparently failed to interview a number of key witnesses in their initial investigation, which makes it seem like a rather cursory matter that they chose not to pursue.
The way they are held accountable for that is often through public outrage and government pressure, which only came when it was divulged that Hockey Canada had been paying people off through a sexual assault slush fund.
This is not uncommon in abuse cases, either. Often, you'll find serial abusers (like Weinstein or Cosby) have indeed been accused and lightly investigated/cleared in the past, and it takes public pressure to conduct a serious investigation that eventually produces a conviction.