Did you actually read what you linked, or did you just paste in a random link from a search engine?
There are two methods presented: one only backs up the camera roll; the other requires plugging into a computer and manually clicking around, at which point you might as well use the first party backup built into Finder (or iTunes on Windows? Is that still a thing?), no random third party application needed. I also highly doubt their “backup every single content” claim.
It’s also a sneaky marketing article for that third party application, following the common SEO practice of giving you a half-ass solution capturing a frequent search term (in this case, “backup iPhone to Synology”), then plug their own questionable thing as the better solution.