I can’t imagine that the amount of pressure applied to chalking your cue’s tip, regardless of whether you power cored
the chalk drilling a hole in it, could ever approach the amount of pressure needed that “could” ever flatten a leather tip.
This sounds absurd and even when you hear players squeak the chalk, it isn’t going to flatten their cue’s tip doing it.
Over chalking creates a mess & could lead to uneven cue tip contact with the cue ball because of caking but flatten the
tip, that sounds like some fairy tale some old timer told a newbie years back the first time they ever visited a pool parlor.
It might not flatten the tip but it definitely wears it out like more than twice as fast.
For a while I reverted to bad chalking habits and started boring the chalk again. I went from needing a tip replacement every 4-5 weeks to every 2 weeks with the same amount of play! Once I realized this was the culprit I went back to stroking the chalk on and bam the tips last 5 weeks again.