Just because a light rushes across the map doesn't mean they are a Suicide Scout trying to get a Scout award. I frequently rush the enemy in my T50 for the sole purpose of sewing chaos. If you can get them to waste time trying to kill you it gives your team more time to get in position. That means the slow heavies also have more time to catch the faster support tanks. It tends to string the enemy out so when the forces meet, you end up with a concentrated force against a strung out force. The trick is to never stop, even for arty. You also don't stick around too long. It's better to disappear for a bit and then return later for any arty you may have found. This tactic does not work on every map, and sometimes you have an idiot team that doesn't take advantage of it, or you get killed early and end up looking like a normal idiot scout. When it works though it's a thing of beauty.