When you Erode your own Land with Earthbent +1/+1 counters, a number of things happen
M15 has some bad raresI doubt that Grindclock is going to turn any heads at the next Pro Tourbut for the most part, each rare in the set is useful in one way or another
This mono-green Bear grows with the more lands you play, while also accelerating you up in lands by returning yours from the graveyard to the battlefield when it comes into play
Umezawas Jitte (Equip Artifact) Versatility is why [c]Umewazas Jitte[/c] is banned in Modern, and why it sees heavy play in both Legacy and Commander
Ill issue my standard disclaimer that any kind of supposition engaged herein is not a prelude to anything that the Commander Rules Committee (RC) is thinking about
Yes, there are a few exceptions to this rule (such as Funeral Charm), but it's only a few cards out of the hundred plus that have been made