This keeps backups efficient since you can ask the filesystem to only send the changes instead of going over all the files and figuring out what has changed, so it’s probably a lot faster.
I use borg with borgmatic. I just back up / (which includes home) and exclude some folders I don't want (like /mnt or /tmp).
It does the same as you just said.
I have 20 borg snapshots of my nearly full 1tb drive which takes about 400gb of space on my NAS.
I do it at the file structure level, not at the block device level as the article suggests. Why would I want to back it up at the block device level instead?
It's a pretty good deal compared to proton mail pricing at least. But be aware that starting from the second year it will be 96€, as the deal is only for the first year.
https://en.m.wikipedia.org/wiki/Nonprofit_organization