Stop raking the balls with your shaft. Shafts don't nick unless something hits it. Period.
While true, there is something to what he is saying. Most shafts these days are pretty poor quality maple. As a result, they are softer than shafts of the past. Dings and nicks are harder to avoid.
For example, using a plastic bridge head...a shaft shouldn't get a series of tiny nicks in it from simply shooting a shot or a few shots. Some shafts do. This is because as a shot is being stroked, the shaft vibrates after the hit and it dings itself down the shaft on the bridge head. I'm not talking about carelessly dropping the shaft onto the bridge head.
There's probably no one on this Earth more careful as I am about this stuff. None of my shafts have any sort of dings on them. I'm obsessive about it. They feel the same as they did the day they were new. Sometimes better - more slick.
That said, there's a lot of shafts out there that are too susceptible to getting nicks. There are others which are much more forgiving because they are harder. Raking balls is a bad habit. But how about using the end of the shaft to position a ball down the table? And doing so gently? That shouldn't ding a shaft. But some poor maple does, just like in the example of using the bridge. Normal play conditions shouldn't lead to dings and dents.
The older shafts from the 80's and before in a high quality cue were much harder. Had to basically let the cue slip and bump a sharp corner for the shaft to get a ding. I don't see maple like that anymore. Real bright, lot of growth rings, really hard, extremely straight grain....
Most of it today is junk that cue makers of the past would never have used for a shaft, maybe not even for a forearm. Which is another topic...what's up with all these "rock" maple forearm cues that play like a wet noodle? I'll tell you what, that maple is soft.
This has lead to a lot of interest in laminated shafts or shafts with various space age cores and inserts, as well as laminated butts, or coring the butts with harder woods like ash or other materials. Doesn't stop the easy denting. Predator shafts for example ding very easily because of the poor wood they use in those. But at least these various laminated shafts take care of the mushy, flimsy feeling hit problem associated with low grade maple.
Another thing various cue makers, both production and semi-custom do to deal with the mush hit is to use stronger tapers. I hate most cues out there these days because they have tree trunk tapers to compensate for the softer wood. Used to be you could get a genuine thinner pro-taper shaft that was also really solid hitting and crisp without hitting like a Meucci. The last modern cue I hit with that had a good long taper on it, and was a thinner diameter shaft which still hit solid was a Samsara. Probably 15 or so years old.., but the shaft on it was excellent grade wood. It was just that one, other Samara cues are not like that. Beyond that, it's been a few select customs. And even nice customs from various big names these days do not have wood as good as some production cues did from the late 1970's.
It's kind of a bummer. Times change. That's why these guys with older, high quality cues value them so much. Play with a particular shaft for 10 years straight, and you have an intimate knowledge of it's feel, sound, hit, performance and all that. Do so with a good shaft, and it's even better. These days, there's no putting 10 years of play on a shaft. They break down. They "loosen" up is what I like to say. Surface of the wood deteriorates. Hit gets mushier than they originally were, which was bad to begin with. How come a Szamboti with at least 20 years of play on the shaft still hits great? It's not because these guys were some super geniuses of cue construction and the secret has been lost since. They had better wood. Simple as that.
Anyway, sorry for the rant and side track. Just my $0.02 on why cues tend to ding and dent a lot easier these days.