We can sort Cross-world Linkshells (CWLS), but we are not able to do it with normal Linkshells (LS).
Since Linkshells comes and Linkshell goes, we should be able to sort it there too.

Will this be implemented in 6.0 or what is the reason we have it in the one
menu / window, but not in the other one...?

I think it would be a small, but necessary QoL