Goblin Tutors Goblin Matron, Goblin Recruiter, Moggcatcher Goblins have been a force to be reckoned with in Commander for over a decade, traditionally headed by cards like Krenko, Mob Boss to make dangerous swarms or Purphoros, God of the Forge to inflict massive damage to the table in and out of combat, but plenty of other color combinations and strategies are quite viable too
The Motherlode, Excavator Mono-red just lacks the energy production to fuel The Motherlode, Excavator, and its a pretty weak payoff anyway
On top of that, the card itself was considered the most powerful in the game and was highly coveted for that reason
[C] Union Gain: Attach up to 2 [W] Energy cards from your discard pile to this Pokemon
The first player is usually heavily advantaged in modern Magic, and designs like Lonely End and Sylvan Smite give the second player more stabilizing potential when playing from behind
Nature's Claim gives the opponent some life, but there are plenty of decks that couldnt care less about a little life if it means destroying something like Leyline of the Void