Tvheadend

No. The reason for this is that the multiple ACL lines per one user are supported to merge (group) things like:

1) network ranges
2) profile
3) dvr configs
4) channel number ranges

And if you have multiple lines per user, it's very confusing that you need to modify password for each these entries. It's even more confusing than separated authentication.

Also, for future, this scheme allows us to use another authentication layer like LDAP, database or so...

Another benefit is that you can have multiple passwords per user :-)