Why did DBZ stop stating power levels?

Not sure as to specific reasons from the creator but why would you? After the Vegeta/Nappa saga, numbers just began to multiply like no tomorrow. First power level 9,000~20,000 was insane (enough to blow up a planet). Then you hit the Ginyu force and they're like what, 100K+, then Freiza is 1m, but a super saiya-jin is 1m+ (to defeat freiza) now everyone is more powerful than a super saiya-jin by leaps and bounds and you're getting to ridiculous numbers like 100 million. You would think at such high levels, fights would be a whole lot different (e.g. damage to the environment, blowing up planets by blinking) but such is not the case. Makes sense to not say what levels they are so that the fighting can somewhat be kept the same throughout the series.