I have no knowledge about the other case you mention.  I looked up the case and the person responding to that question could not identify the beetles.  The insects in your picture are also beetles but is an equally poor picture for identification.  There is no identifiable similarity between the beetles in the two cases.  

There are no other reports of this happening that have come to my attention.  I do not know if they were able to reduce beetles entering the chimney from using a mesh.  The beetles in your picture do not appear to be a beetle associated with structures because they appear (photos can be deceiving in regards to size) to be too large, and do not have an appearance of typical beetles that are structural pests.  Normally, I'd agree with the PCO that it was likely coming from the firewood used in the fireplace; however since you state there wasn't any wood used, then they cannot be from firewood.  

I suspect the beetles have used the fireplace and chimney as shelter from the cold nights we have had recently.  They probably were active during the day, flying about looking for plants (trees, shrubs, other - hard to say without being able to identify) and as it cooled at night they wanted to be warm.  Your chimney kept them from the harshness of the colder night temperature but when they were ready to begin their day again they were disoriented or unable to reorient to fly up and out of the chimney.  Consequently, they flew into your living area.

I do not think you would need to worry about this beetle being a structural insect pest.  This beetle could feed on trees or shrubs in your yard when the plants produce sufficient foliage.  If you are still concerned, you could submit samples of the beetles to one of the county extension offices for someone to take a closer look at them.

Hope this helps.