Red Hat Enterprise Linux 8 introduces Application Streams. Software Collections (SCLs) are no longer needed in RHEL 8. According to Introducing Application Streams in RHEL 8, Application Streams, containerization, or virtualization can be used to fulfill needs met previously by SCLs.
I recently updated PHP and Apache httpd on a CentOS 6 server with Software Collections. Software Collections allowed installation of multiple software versions. Software depending on older versions of other software can continue functioning, while other software requiring new versions of that other software can be installed and used. SCLs helped me gradually transition my PHP applications from httpd+mod_php to httpd+php-fpm.
With anticipation of CentOS 8 soon being available through my virtual server provider, GoDaddy, I wanted to become familiar with RHEL 8. I wanted to deploy CentOS 8 for my next virtual server, and I wanted the server to use httpd and php via SCL only. I am now rethinking my plan to use SCL on CentOS 8 to allow future transitioning of applications toward newer software versions at a pace I control.