Human nature is flawed, people can sin, etc. so no place, group, or organization is 100% good or free of sin and evil.
However, some groups make bad choices (leadership, mission statement, position) which tends to attract an above-average amount of evil and corruption.
For example: the most ideal Trad chapel could have a couple bad eggs, "because human nature" to use the modern parlance.
But some chapels could have worldly people, heretics, and other problems *because of the organization that runs the chapel*, or because of the priest's leadership, etc.
In such a case, it would be worthwhile to find a better chapel.
But by confusing these two situations, all kinds of errors result: Especially giving up completely when you shouldn't.
Just because there's a bad apple in every bunch doesn't mean you can't find a barrel with only 1 bad apple (instead of 10 or 20). Or a barrel with a bad apple by accident, rather than bad apples that pretty much HAD TO BE THERE based on an organization's charter, priorities, principles, or other fundamental reasons.