I don't know where people are getting these "tiers" already. There isn't a lower tier deck just lower tier cards at this point and it just happens Monsters are up there. And the reason they're up there is not just easy - it's because they're unique.
I can make a solid deck to deal with any other the other three factions easily, even Northern Realms (I don't get where people think Northern Realms is hard to deal with - it takes a ton of turns to finish a combo. If you can't at least partially stop it then you've got bad luck or a bad deck). But Monsters I needed to make a deck basically completely to deal with those, and even then I have to rely a lot on draw. Because it is very easy for Monster decks to get a ton out on the field while at the same time crippling your side. They're pretty much the only deck that actually uses weather. They can get copies out far faster than any other deck, even NR. And of course that ridiculous Eternal Gold Card issue - there really is not reason is should work on Gold Cards in a deck that can technically have five Gold Cards.
I can make a solid deck to deal with any other the other three factions easily, even Northern Realms (I don't get where people think Northern Realms is hard to deal with - it takes a ton of turns to finish a combo. If you can't at least partially stop it then you've got bad luck or a bad deck). But Monsters I needed to make a deck basically completely to deal with those, and even then I have to rely a lot on draw. Because it is very easy for Monster decks to get a ton out on the field while at the same time crippling your side. They're pretty much the only deck that actually uses weather. They can get copies out far faster than any other deck, even NR. And of course that ridiculous Eternal Gold Card issue - there really is not reason is should work on Gold Cards in a deck that can technically have five Gold Cards.