One thing about rear drags is that they are attached directly to the main shaft and if you get just the slightest bend(wobbly spool syndrome) the drag is useless. Rare but it does happen from regular use. Though i have had it happen only once, but you guessed it, it happened when i really needed it. I took the whole system appart and cleaned and reoiled it. But it still didn't work. Then i noticed the shaft just barely off center. But it was enough to ruin it.

If you bend the shaft on a front drag system it doesn't matter cuz the spool and drag are one working unit and you almost never bend the very top of the shaft.