I suppose you don’t find Stonehenge all that impressive either. Sorry, but I do, considering what the respective societies had at that time.
The builders did a decent job with found stone (they don’t look like much work went into them, apart from selecting them for their existing sizes), but that’s literally the only stone church from the Viking era on Greenland. It’s still possible they had 25,000 population at their peak, but the structures must have been of timber, and of modest size, as this stone one is.