Well you can tell that to the creators of, atleast, earlier version of unreal engine (and based games) where functions ForEachDynamicActors are all over the place.
Next they are talking about not using the method in everyframe or Tick which is reasonable. Incomplete information is usually more dangerous than no information!
Last, it is not written that all the said functions are called at once and we really have no clue about the clustering of said functions.
Conclusion: The judgement of good or bad rests until the source is really revealed.
I’m not aware of a Dynamic Actors list in UE4 (it may still be there, I don’t know), but in most of your prior engine games, the DynamicActors list is extremely small compared to the AllActors list.
Any type of batch actor retrieval is slow… in a “don’t use this in a tick” kind of way. But there are plenty of times where using it is safe, and clean.