And herein lies the immaturity the grandparent was talking about.
"starting with true premises and employing sound logic will always produce a true conclusion"
is only useful where premises can be determined to be true, and the conclusion follows a logical syllogism end to end.
This is only done (or even achievable) for quantifiable / statements of fact ("a book is on the table", "the earth is round", "the GDP is 10 trillion" and the like).
For 99% of what humans care about - claims and their veracity, values, morals, politics, goals, tastes, aesthetics, interests, etc, there are no "true staatements" to begin with, and many of them doesn't involve a sound logical syllogist-sound process, but only regarding their simplest sub-parts.
E.g. two political enemies might have different opinions on what to do with the national debt, but they can agree on the actual amount of the national debt, and use pure logic to calculate it, check where it was spent, etc. That, though, wont help them determine logically and agree on whether something like welfare or military spending is good or bad, and it's usually those latter questions that matter in such discussions.
The thing is, people still name all those other things (that are not ammenable to logical process end to end) as true and false, based on their own opinions.
Logicians can disagree all they want, this ain't gonna change.
And it's those "true" and "false" statements that matter in most arguments, not their less interesting, quantifiable, easily acceptable by everybody and logically analysed brethen.
The "let's point people to logical fallacy lists, as the solution" crowd doesn't understand this.