There is a lot of useful advice on the Internet. And there is a lot of bad advice. The trick is to identify which is which. As with any research, the best approach is to find multiple sources. It’s also helpful to spot indicators of bad advice. One of those indicators is the recommendation to “disable SELinux” .
I often see this gem when reading forum guides explaining how to configure or install some application. When you see it stop reading and find a new guide. This indicates that they don’t really know what they are talking about. SELinux is part of the RHEL security strategy and there is no good reason to disable it for normal server operations. If it is causing a problem, and it sometimes does, then fix the underlying policy. Don’t disable it.
It is, however, often useful to temporarily set SELinux to permissive mode while debugging or performing a complex install. This guide to fetchmail shows what good SELinux advice looks like. If you read something like this it is probably good advice.