Trent Horn gives this analogy in his book Why We’re Catholic as well as in this article on Catholic Answers:
"…But if people can be saved if they don’t know Jesus or his Church, then why bother telling them about the Faith at all? Don’t we risk their souls by giving them an opportunity to reject the gospel? Consider this analogy:
Imagine you are trying to help people cross over a river that has partially frozen over. The river is shrouded in fog and when people choose to walk across its icy surface they disappear into the mist. Did they make it across? It’s possible they safely made it, but it’s also possible, if not probable, that many of them did not make it across. Let’s say, however, that you knew about a bridge that safely crosses over the river. Even if they might reject your offer, wouldn’t you still tell people about this safer and more certain way to get across the river?
That’s why Jesus commanded his followers to “make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Matt. 28:19)."
Just because there may be a possibility of salvation for those outside of the Catholic Church, it doesn’t nullify the truths found within it. Jesus came, and left us a lasting “city on a hill” that guides us towards Him.
One of the beautiful tools that He has given us to help us on this journey is the ability to receive definitive absolution through the sacrament of Confession. Why would we want to ignore this and just go it alone and just hope for the best?