It can't hurt. Think of it as top feeding.
It can hurt. If the soil you are adding is alot and not aerated it can rot the stem base off. Alot of people using aerated soils /mediums haven't experienced it but if you topdress too much in conjunction with non aerated soil it can rot the stem off and sever the plant
This is my opinion though
I'd much rather only top dress 1 or 2 inches at a time, during a transplant I'd like to keep the root ball higher than lower if that means getting that hardened off stem too low
But also I do like to always get the stem at least an inch Down on a transplant and 2 or 3 inches max.
Be more careful in a humid environment or using compact soil
Top dressing is great but to an extent