I use Linux Mint on all of my home computers. I personalize all of them to my needs and I do not find it hard or difficult or time-consuming. I find the installation process straight forward.
Perhaps however you have more intense personal customization needs than I.
Just a hunch, but he probably means disk partitioning, allocating a partition for swap and other such stuff you can customize most easily during installation.
It's nice to have excellent options for that, but I seriously don't have that as a deep need right now personally.
Perhaps however you have more intense personal customization needs than I.