Actually, if you look
here, the sphere containing the Defense Body is basically on the horizon. Small town size is more like city sized. A hammer the size of building is more like the size of a mountain ... StrikerS may lack the giant explosions seen in the previous seasons, but remember Nanoha was able to block a (over?) S-Rank attack with her round shield without trouble at all. She later matched Dieci's more powerful blast with Exelion Buster in an AMF. Strike Stars >= Exelion Buster. SLB in A's was a S Rank attack ... Power inflation to the max.
Multiversal threats in the original series and A's to anti magic to counter the main cast in later seasons, lol. Vivio was also powered by
this in StrikerS.
One thing I also think is ignored is Nanoha sealing an energy reactor supporting a multi dimensional quake with her power and Lindy suppressing it with a barrier. That's also crazy.