Hearthstone opening strategies: why waste mana?

There are various articles on Hearthstone opening strategy which suggest it's a bad idea to use early-game spells and summons to damage your opponent directly, and that you should instead save them for minion removal.

An example: your starting hand contains an Elven Archer, a 1-cost 1/1 minion that does a point of damage when summoned. I've seen it advised that if going first, with that card in your hand, you should not play it, but save it for minion removal.

Another example: http://hearthstoneplayers.com/4-steps-60-win-rate-ranked-constructed/ Going second against a Rogue with a 2-cost 2/1 Loot Hoarder, Deathrattle: draw a card in your hand. The advice was not to play it and save the coin, because on her second turn, the Rogue can generate a dagger and kill the Hoarder.

I understand why, in most circumstances, it's better to remove a minion than damage the enemy. What's bugging me about these particular opening examples is why they're a better idea than doing nothing and ending the turn.

In both cases, you've wasted a point of mana, and the chance to take the initiatve. By having a minion on the board first, you can use the following turn to attack with that minion, possibly removing an enemy summon and leaving you clear to summon onto an empty board.

The Loot Hoarder one I find particularly puzzling. If the Rogue gets a dagger and kills it, you still have the initative, you've forced the Rogue to make what's possibly a suboptimal turn-2 play, you've done 2 damage to the Rogue and you got a card into the bargain. Sounds like a pretty good use of the coin to me.

What am I missing here?