I agree that Thorn of Amethyst doesn't merit 2-4 slots in the general metagame (see my previous posts). Please note, I was trying to address (and I failed) the reason you gave for why Thorn doesn't merit play in Merfolk, which is entirely different from whether or not Thorn should be played in Merfolk. There are much more relevant reasons to not play Thorn.
Addressing the viability of the E-tutor package directly, I wouldn't even run it in UW Merfolk (even if it is perfectly capable of doing so, the idea is that it doesn't usually and certainly shouldn't), Merfolk has much different issues to worry about. Essentially, even if there were a combination of cards that increased our odds against Storm by 30%, but had little effect on other matchups, I wouldn't advocate it -- particularly when there are other options that impact Storm and remain much more useful in other matchups. The important argument against Thorn is that it is too limited in scope, not that we lack an E-tutor engine.
Land -- 20
16 Island
4 Wasteland
Vials, Phials, Ampules, Ampuls, Ampoules, 1cc Artifact-Bottles -- 4
4 Aether Vial
Folk -- 24
4 Cursecatcher
4 Silvergill Adept
4 Lord of Atlantis
4 Coralhelm Commander
4 Merfolk Sovereign
4 Merrow Reejerey
Permission -- 12
4 Daze
4 Force of Will
4 Spell Pierce
SB:
2 Relic of Progenitus
2 Tormod's Crypt
3 Back to Basics
3 Umezawa's Jitte
2 Echoing Truth
3 Mind Harness
I was so used to Standstill (and so fond of its triggers) that it actually took a while for me to even consider testing without it. Obviously, most people abhor the idea of not having direct CA generation outside of Adept. There are, of course, other ways to produce CA, and more importantly, there are also other attributes to the game which are comparable in relevance but different from CA which merit consideration.
I found Standstill to be either too conditional or win-more. Spell Pierce replaced it in my view. Spell pierce isn't nearly as conditional, and it directly strengthens the viability of the Lord-route. With so many Lords, I can very often outclass my opponent's board, I just need to make sure that my Lords can live through removal and avoid bombs. Spell Pierce is much more flexible than Standstill as well; it usually answers the spells I am most concerned about in a matchup.
The lack of Mutavault will also be very questionable to some. Without Standstill, it is less necessary. Its removal affords me great consistency and more space in the deck. If I were to play Mutavault, I'd need to move up to 22ish Land, imho. Removing mutavault buys more slots in the deck, and improves the ability to open with an Island to some extent. This version is also somewhat blue-mana hungry. Mutavault is also a risk which might not be worth taking without Standstill. ~42% of Legacy tournament placing decks use Wasteland. Even with my own Wastelands, Mutavault is very difficult to protect. I have absolutely loved avoiding opposing Wastelands and breaking the symmetry of Back to Basics so extensively.
This is basically what Elves.dec or Relentless Rats.dec wish they could be.
peace,
4eak