I certainly would not recommend that a Sorcerer playing Swordflight take Focus feats just to benefit a single sporadically useful spell (at most two if one uses Burning Hands as an anti-troll weapon). I suppose for a Wizard with some feats to spare after focusing in a more generally useful school like Necromancy or Evocation the utility of Transmutation might be at least arguable, though I am doubtful Flesh to Stone would really work noticeably better than alternatives from other schools.
Pretty much. Whizard seems to be thinking of modules where you have a substantial number of low fort but important enemies who are immune to Death Magic but not to Petrification...which I've never run across.
You yourself made that statement...
... and when given a setting (one that you cited) you acted as if you never said that, and then want to go back to treating everything like the standard creature.
I think you're confused here. I've generally run across two scenarios:
A, author uses default creatures or close to it. Result: nearly every enemy that is Death Magic immune is also Petrification immune (golems and undead).
B, author does what they see fit balance-wise and gives important (and/or difficult) enemies protection from insta-kill attacks. Result: nearly every enemy that is Death Magic immune is also Petrification immune (whether via items, scripting, or massive Fortitude saves).
Either way, stuff immune to Death Magic (literally or practically) is usually immune to Petrification (literally or practically). Pick your poison.
The variation of saving throws from monster to monster on any module is a lot greater than a span of 3. Arguing that necromancy has a place where the +3-+6 boost from focus matters, and flesh to stone does not have such a place is a little absurd. It's like saying that wail of the banshee is absolutely worthless if you do not take the focus feats.
There are modules where Wail of the Banshee is worthless without the focus feats (or rather, not worth using compared to other spells). Huge difference between killing 3 out of 20 enemies and 9 out of 20 enemies. Or 13 vs 19. And that boost can easily matter without +6 to Flesh to Stone mattering by a simple reason: Flesh to Stone is 3 lower DC and single target. Against a single powerful enemy (assuming the enemy is even vulnerable to these spells), a 20% chance to insta-death is much, much better than a 5% chance, or 25% vs 10%, or whatever. And against a bunch of weak enemies (with presumably low saves) Wail can wipe out the entire pack (or close to it) while Stone to Flesh is still just one target.
Given that all the other reasons you mentioned were off topic anyway, I don't think tiredness has much to do with your reply.
No, it was completely on topic. Go reread your own statement (or here, I'll help): "Like death magic and most necromancy, flesh to stone relies on fortitude saves. If there is a severe issue with a caster not having a high enough DC then your statement goes both ways."
Second reason points out how Finger of Death can be used as a single target nuke (for a rarer damage type that doesn't allow a reflex save). If they fail, they die. If they succeed, they still take a decent chunk of damage (even those "20/- to all damage and 100 in each save" bosses). With Flesh of Stone, if the enemy fails, they die. If they succeed, nothing happens. That's a reason to favor focusing on Necromancy over Transmutation *unless* Flesh to Stone is effective against individually dangerous targets that are immune to Finger of Death. It also mentions how Wail is an AoE...and thus (in addition to higher chance of killing *something*) is actually well suited for a bunch of weak mobs unlike Flesh to Stone.
Third reason points out how you get more of the relevant Necromancy spells. Most people will skip Greater Ruin because, in spite of being a blast of 61ish or 122ish positive damage in one go (and thus piercing stuff like 20/- bosses)...it's simply not worth the feat investment for only one use per day. So clearly there's a limit -- if you were limited to casting one Flesh to Stone per day I sincerely doubt you'd advocate Transmutation. Whatever you think that limit is (somewhere between 1 and level 6/7 spells), it's certainly on topic.
Fourth reason points out how Necromancy helps with other spells still even if the "save or die" aspect is rendered moot. We're comparing Necromancy and Transmutation focus as a whole in the thread (and part of the problem is that Transmutation focus as a whole...is really just Flesh to Stone).
Again off topic, unless you can show that a mage can only reasonably focus in one school of magic, or that evocation or some other school (besides necromancy) is more worthwhile focusing in than transmutation.
Evocation usually is, particularly for AoE spells. Even if you have to spam IGMS against bosses the minions are usually vulnerable to things like Firebrand, Cone of Cold, Chain Lightning, etc. And if you're in a module where everything has a zillion saves and resistance then both Evocation *and* Transmutation focus are worthless (along with every other focus).
Even Enchantment (Dominate and Hold spells that attack Will) and Conjuration (things like Flame Arrow, Acid Breath, Evard's, Cloudkill, and Acid Fog) are usually better than Transmutation -- again, because Transmutation affects very, very little that isn't already covered by Necromancy. If Necromancy didn't exist (or if Flesh to Stone did something like attack Reflex) then Transmutation would be much more valuable.
Just answer the question, because none of the modules you listed have any implementation of immunity to flesh to stone.
They don't need to, because as *you* said...
"To that end the burden of proof still lies on you, to show that flesh to stone is in fact a less feasible spell than both the necromancy and evocation spells that require focus feats."
Necromancy and Evocation spells (with foci) are far more feasible in those modules than Flesh to Stone.
P.S. Apparently Swordflight does have that implementation.