I've put off updating R for a couple years now since the last time I updated R, I had a problem with the packages not loading correctly. I now feel the need to update R.
For Mac users, what is an easy and package-problem-free method to update R?
It’s unclear what problem an installer is designed to address other than enabling installation under badly outdated macOS versions. Navigation to CRAN, two clicks to download and then point the finder to the pkg file in Downloads, click and follow the prompts is not difficult.
No, and loading already installed packages should not be an issue, absent corrupted files. The most-frequently encountered difficulty with packages for macOS users is attempting to install from source. This is seldom necessary in the usual case when presented in install.packages or update.packages with message "a binary version is available, but there is a later source version".
Sometimes the source version will install without difficulty; often, however, it will throw an error. In the latter case, the fix is simple—go back and select n, instead. macOS binary versions on CRAN usually lag 7-10 days is all.
Anaconda a well-regarded as a package manager for Python can be used as a package manager for R; however, it has been a frequent source of installation trouble for R and cannot be recommended for that purpose.