There are so many +1/+1 counter synergies these days that its incredibly easy to make an oppressively powerful deck with that strategy, and I personally dont like the mental energy required to keep track of all the various triggers those strategies accumulate on the battlefield
The shopping behavior around this card doesnt look particularly suspicious, so most likely, Lumras rapid ascent in value can be chalked up to collectors realizing that it was illustrated by the same person responsible for Base Set Charizard
Then, the spring set would be a large set that took place on a different plane with different mechanics
This means if one creature dies while both are in play, your opponents will be forced to sacrifice two creatures
Then the 1-drop 1/1 dork has flying on your turn and then also taps for but can only be used for equipment - easily done here
Red offers some powerful enchantments like City on Fire and Aggravated Assault that enable a more aggressive strategy compared to the often-controlling enchantress decks