Well no. It ain't completely crap.Your advice and comments do have valid points of course. The harvester if it makes back to the refinery it gives the entire team 300 extra dollars to spend. Add that amount to the constant stream of low income, the better players with higher score are definately going to purchase some heavy firepower. So your suggestions are of course valid despite being a bit obvious.
Even if you fail to destroy a harvester. Players at the start of the game can earn easy money in at least damaging it. C4 it, flame it! Grenade it! Even though the pulse rifle might seem like a poor choice against the harvester but you'd earn a couple of easy 100 bucks which are critical during the early stages of the game.
In a late game, I suggest if possible try not to destroy the enemy refinery if your team is holding the enemy under seige. The points from constantly destroying out going harvesters can be crucial. And in my experience has been the victory factor when the enemy had it's back against the wall and was giving a heavy defence.
In one game on Walls. My NOD teammates had the GDI's refinery and Factory taken out. However despite this, NOD lost in the end as we had no vehicles to counter(Airstrip was destroyed) and the GDI troops did a good job of defending the base whereas we couldn't get in. And there was no harvester coming out to be destroyed. And in the end NOD lost by about several hundred points.(Both teams had about 10k points total)
So my advice is don't take out the enemy refinery if possible.