That's definitely not true. There is strong market competition, so the tools are highly optimized. In fact if you have written logic that vivado detemines is impossible to reach it removes it, and everything connected to it, and so on. I've seen it do really amazing optimizations this way and it's all to save area. So while being inefficient it may seem like a sensible thing to do in a monopoly situation, there is a healthy duopoly, the tools squeeze every last bit of performance out of the device. Tool performance is a selling point.