I think you are missing the point how easy is to fuck things up in a console

No i think you are. Why should a beginner ever even touch the CLI? You can also SSH into the synology and fuck things up.

Using a ‘friendly environment’ like synology is not gurantee to not fuck things up.

Installing truenas when having no idea about almost anything is cumbersome, dealing with the millions options (some of them incompatible between them) is frustrating, cryptic error codes are discouraging…

What millions of options? You select a drive, and set a password and your done? 1 Set fewer then on synology.

You brought up TrueNas. TrueNas for example also gives you safe boundaries and suggestions how to set up things. Same as synology. There is literally also a setup wizard for backups.

AND AGAIN just because you follow the synology wizards does not mean your data is safe either. You always can fuck things up if you want to.