Because I'm extremely cheap. My system works fine at the moment. When I put a Moca signal on the TA, I'll know right away if it caused a problem. I just wanted to know if there was a 100% chance Moca would interfere with my TA or not.The problem is that many Tivo issues I've run into can be very hard to diagnose and figure out; so why not go with best practice? The folks here are saying you need it there, and people aren't having problems if they follow the advice, so I've got a POE filter there!