They did away with button mashing, you can niw hold down the button to do attacking/mining/cutting now. If you combined that with gaining exp from punching a rock it would be very broken. Just afk with the button held down.

I agree with getting rid if the mechanic, it was exploited. While stationary target practice may be a part of training, you certainly shouldn't be able to master skills with it alone. That would be like hitting a punching bag and nothing else making you a professional boxer.
It makes more sense to engage in combat anyhow, actual combat practice and loot, and if you're the sort who previously just afked with a button mashing macro, you might as well just of used dev commands to cut to the chase since you weren't putting actual effort into it anyhow.