Thank you for this. As a parent who ran lines, I always tried my best and limited my signaling to only what the referee had stated in pre-game and no more. Since I was the most willing volunteer, I'd wear my cleats to each game to keep up with play (which was also good during warmups with the kids), but have to become dispassionate about the teams (which was not fun at all, but a required mind-set on my part, even though I was just signaling when the ball out of play), but I always figured I was helping, and that felt good. Like donating blood or serving jury duty, I always thought of it as my (civic) duty to the game I love...
^ Actually, you reminded me of the one time it came in extremely handy to use club lines. It was a state cup game, and it turned out that the away team's club line was an assignor down in central NJ! He actually took my contact info after the match and put me on a tournament he was assigning a few weekends later. I've been doing that tournament annually ever since.
I am in the "in the don't use club linesmen" group. Cost always seem to outweigh the benefit. There are mechanisms for dealing with in inexperienced or bad certified linesmen. Usually a different type of pregame (more discussion on mechanics and/or rule interpretations) or discussion with the local assignor does the trick respectively.
Yea, they really don't have a clue as to how the Ref / AR relationship works. They don't realize how bad they can make a referee look!
I had a U14G rec game the other day. One of my ARs got held over on an earlier game. I knew she was there, so I left a flag on her line and started without her thinking that, by the time I got a club line and gave instructions, etc, she would be there anyway. My assignor showed up and jusmped in for about five minutes until she got there, but told me to never start a game without a least a club line.