^^
I couldn't disagree with you more on this. I've managed environments from 200+ filers and up and we manage via snapmirror.conf file and local snapvault files. I've only recently managed snapvault, (only vault portion), the mirror is still managed via .conf files. But i've also written custom front ends to handle this fan out management via the .conf file with extensive powershell scripting via the API's.
Here's a case in point, if you lose your OCUM centrally manged server to a patch, and you aren't prepared for a failover, non of your managed jobs run. The only thing, we currently use ocum for from a mirror perspective is alerting on the datasets. I will take fan out, conf file management any day. But you need to have the proper controls in place.
If you are talking about a mom and pop shop with a small number of filers, go for it.