Of course, I am not disagreeing with that in any way. 
I was more just clarifying the difference in the meaning of the word simple as it relates to systemd-boot. Personally, I don’t use systemd-boot because it is easy. I use it because I like the simplicity of it. Because it lacks complexity, it requires very little knowledge to troubleshoot. Also, once you learn how it works, there isn’t really anything left to learn. There is file with some overall settings which is usually less than 5 lines long. Than there is an entry file which has a handful of config for each entry. Once you know those two things, that is pretty much everything you need to know about systemd-boot. There really is very little beyond that. Just a command line tool with a handful of options you can use to install it or check the status.
Compare that to something like refind. Refind is very easy to setup, it practically sets itself up. In my experience, it is also far more resilient than grub. That being said, when it does break, troubleshooting it takes more knowledge than something like systemd-boot. On the other hand, refind has much more functionality than other bootloaders. It can boot virtually anything. It is one of the few bootloaders than can easily handle a mixed legacy/UEFI environment.
In the end, it all comes down to personal preference. Asking, “which is the best bootloader?” is a bit like asking “which is the best filesystem?” or “which is the best DE?”. They are questions without answers. 