There is another card which is similar to cantrip-trasher; Raze. It allows to trash from 4 cards (instead of 5), non-mandatory; it can trash itself when you finish trashing Estates. It is 2-cost .
Raze is non-terminal but not an unconditional cantrip. And even when you use it to trash an Estate it only draws the card afterwards.
Sorry to be so blunt but this kind of argument is as nonsensical as me claiming that Lookout is like a cantrip trasher because it is non-terminal and trashes a card from the deck so like with a cantrip trasher you are left afterwards with 4 cards.
