My two cents is that ramp, tempo and advantage are all part of a spectrum - they're making your plays more efficient, your deck more streamlined, and allowing your plays to have the effect you want them to. To my mind, this is obviously easiest in green, and the most sustainable in green, as there are plenty of big ramp effects and ETB untapped effects.
I think the biggest distinction between ramp and dorks is not being able to use dorks the first turn out. You've just lost tempo playing them, even if it's one mana down on T1, there are still better cards to be playing - the obvious being something like Sol Ring, but otherwise Wayfarer's Bauble, Crop Rotation, Mana Vault - these cards will put your game plan forward, not stall a turn waiting for one extra mana. At best, in that case you're achieving parity, which to me is redundant. For that reason alone, I generally don't play dorks at all. I'd rather have the mana unused on T1 or T2 than draw into them late game, as they achieve next to nothing. This is more true in a competitive meta where tempo can mean the difference between a win or loss. In my opinion anyway.
With all this in mind, I think there is a sweet spot for every deck; obviously anything running green can reach degenerate levels, and anything that combos out for mana too. I think outside of the colours and areas where there is obvious strength, you need to look for advantage in other areas - that's where cards like Necropotence, Mind's Eye, Rhystic Study, Faithless Looting, Mindmoil, Sylvan Library and such are staples - they don't get you mana on the field per se, but they do draw you into answers - the critical cards your deck needs to synergise properly, and if not these, they draw you into land or untap your stuff.
I think in the scope of the game, looking at ramp as isolated from card advantage, tempo advantage and mana advantage is to do oneself a disservice - these are all parts of the same spectrum of gas - getting your deck to its sweet spot in a timely manner, and keeping it there as long as possible. Some areas of play are better at this than others, and I think if you're playing in colours that lack in one part of this spectrum, there are usually options to alleviate this in other ways; that's the key to making your deck really hum along the way it should.
I don't think anything I've said here hasn't been said already, just wanted to weigh in and share my perspective.
I think the biggest distinction between ramp and dorks is not being able to use dorks the first turn out. You've just lost tempo playing them, even if it's one mana down on T1, there are still better cards to be playing - the obvious being something like Sol Ring, but otherwise Wayfarer's Bauble, Crop Rotation, Mana Vault - these cards will put your game plan forward, not stall a turn waiting for one extra mana. At best, in that case you're achieving parity, which to me is redundant. For that reason alone, I generally don't play dorks at all. I'd rather have the mana unused on T1 or T2 than draw into them late game, as they achieve next to nothing. This is more true in a competitive meta where tempo can mean the difference between a win or loss. In my opinion anyway.
With all this in mind, I think there is a sweet spot for every deck; obviously anything running green can reach degenerate levels, and anything that combos out for mana too. I think outside of the colours and areas where there is obvious strength, you need to look for advantage in other areas - that's where cards like Necropotence, Mind's Eye, Rhystic Study, Faithless Looting, Mindmoil, Sylvan Library and such are staples - they don't get you mana on the field per se, but they do draw you into answers - the critical cards your deck needs to synergise properly, and if not these, they draw you into land or untap your stuff.
I think in the scope of the game, looking at ramp as isolated from card advantage, tempo advantage and mana advantage is to do oneself a disservice - these are all parts of the same spectrum of gas - getting your deck to its sweet spot in a timely manner, and keeping it there as long as possible. Some areas of play are better at this than others, and I think if you're playing in colours that lack in one part of this spectrum, there are usually options to alleviate this in other ways; that's the key to making your deck really hum along the way it should.
I don't think anything I've said here hasn't been said already, just wanted to weigh in and share my perspective.