Blocksize is clearly not literally a rate; that's a ridiculous statement. When you artificially cap it, like putting a limiter on your car in your analogy, it can be rate limiting, i.e. limiting the transaction rate - an actual rate. That chart you posted in meaningless in this context, but clearly just greg being greg, trying to manipulate; are you seriously trying to suggest that the tiny increase from segwit shenanigans is responsible for that (cropped) decrease in tx fees? That's demonic.