It is easy to block and kill and isn't above the curve in any way
For example, if youre building a deck around Urza, Lord High Artificer, you probably want a ton of cheap artifact creatures you can tap for mana, and then big heavy hitters you can cast with his second ability and all of that mana you generate
Note they only count cards of their own name Relentless Rats dont buff Rat Colony and vice versa, so pick one as your any number core
Opponents will know what choices opponents earlier in the turn order made, although cards chosen to be discarded this way won't be revealed until they're discarded at the end of the process
Its a bit slow to get going, but you can get a ton of damage with this if it sticks around (and the stat line is also decent for a 5)
Plus, theres the fun of meeting and mingling with other players while participating in prerelease events or different game nights for Modern, Standard, and Commander