It does most of what a Fiend/Maggot does with their EtB effects and then it is better at staying in play, far better at blocking, enables raid, controls planeswalkers and is generally a pain in the arse
Era of Innovation is essentially five mana and several turns to draw three cards, and there are way better forms of card draw in blue
If youre going to play an eight-mana card in Standard, it had better be extremely powerful, and wow does Gisath, Suns Avatar deliver
Serialized cards exclusively found within less than 0.1% of English language Collector Boosters
The Earth Crystal is a counter doubler, and cost reduction, at four mana
The pricing tends to be very close to if not a little better than purchasing it in a store