I agree. A mechanic that players can't understand without a youtube video, and doesn't even guarantee success when you do, is a broken mechanic. I love almost everything about this game, but I genuinely don't know how I can continue enjoying it with progress locked behind this frustrating mechanic.
My biggest problem with it is that it's just so unnecessarily time-consuming. You have to dig out 12 dirt blocks just to take a reading. Then you have to do it like 20 more times to chase the chunk with the highest density. 50% chance that chunk isn't even above 0.03%, and your time is wasted. Then you have to find the deposit underground. Sure, the pick will tell you it's within 6 blocks, but do you know how many blocks there are in a 13x13x13 cube? 2,197! That's a lot of blocks to search! Sure, you could triangulate it, but that doesn't even work if there are more than 1 deposits nearby, which there are, a lot. Your readings will lead you directly between the deposits.
I've even seen people compare prospecting to a full-time job. Having spent 12 hours and still not found any zinc, I agree.