I think John Lawler and others make a good point in that "antonyms" are vague, and I suspect that, despite the descriptivist intent, the question arises from a semantic issue.
From Wiktionary, an antonym is "a word which has the opposite meaning of another, although not necessarily in all its senses." Thus fast is an antonym of slow, but fast is also an antonym of eat. However, most of us wouldn't think about comparing speed with consumption. Useful can be interpreted as "having non-zero utility," which means the opposite of useless. However, useful can also mean "having a positive degree of utility" which is not the opposite of useless. So they are fine antonyms, but not opposite in all meanings. A more appropriate opposite for the comparative version of useful would be harmful or detrimental.
For the more descriptive questions, specifically regarding the "-ful" and "-less" suffixes, I suspect that use of these words depend on how these suffixes are commonly interpreted. "Doubtless" and "useless," for example, imply devoid of doubt and devoid of use. "Thoughtless" and "tasteless," for example, imply lacking thought and lacking taste. The latter pair would be more common in comparative relative to non-comparative use since one can be naturally seen as more or less lacking. The former pair is less commonly seen since it is less logical and descriptively less common (though not unthinkable) to be seen as more or less devoid (of course, cf. emptiest). In general the commonality of use seems to me in line with whether or not it is logical -- so I don't see them as necessarily in conflict.
However, one exception comes to my mind (not saying that there aren't others). When raukh mentioned "impossible" (p = 0), my first thought of an antonym was "certain" (p = 1). As someone more accustomed to speaking with statisticians, for me, it sounds awkward when someone says something is more or less certain. However, I recognize that both descriptively and formally, certain is a comparative adjective. Indeed, it seems that the use of certain as a comparative is more common than the use of uncertain as a comparative, although that appears to be in relative decline.
Additionally -- this is perhaps silly of me to think it needs stating -- choice of which words to use also depend upon the emphasis of the sentence, even for paired words. Whether someting is "more impossible" or "less possible" may, for some, have different connotations. Curiously, those words seem to be converging in frequency of use.
I am guided by the OED, which finds various meanings of distinguish, all of which are ultimately grounded in the sense of classification of things by their characteristics.
In a simple division into classes based on some, possibly unnamed, set of standards, we may say
English grammar distinguishes dependent clauses into relative, comparison, content, and complement.
Here the verb licenses the preposition into.
When the distinction is based on comparison of one class with another, we use the preposition from, noting an actual mark --
Routine violence distinguishes hockey from other sports
or by perception --
He is such a fabulist that it's hard to distinguish fact from fiction in his stories.
In the sense of separating the known from the unknown, distinguish can mean to recognize:
I saw the man from such a distance that I could not distinguish his features.
And it can have the sense of separating the remarkable from the mundane, with the reflexive or the passive:
He has distinguished himself by his scholarship.
The OP's question asks whether there's a difference between omitting and including the word from when we make the distinguishing comparison. Inclusion implies that the distinction is made by comparing things to each other; omission does not. But the difference is often slight for distinguishing a pair of things. Here's an example from a translation of Rousseau's Julie, ou la nouvelle Héloïse (Julie, Or the New Heloise):
P Stewart and J Vachethat (trs) that uses both locutions in one sentence:
The pencil does not distinguish a blonde from a brunette, but the imagination that guides it must distinguish them.
Or consider this example from You Good Me Good by Jing Wang:
Some customers when buy [sic] fish they always like to ask about the female
and male, actually I had no idea about how to distinguish them.
Is there any other way to determine the sex of the fish except by comparing male to female?
Best Answer
In the referred example " no more than " is a way of telling "simply, just, only" in an otherwise emphatic way to drive home the assertion or negation.
MORE is the comparative form of " much & many". So it carries its normal meaning in this respect. It also means greater quantity/degree being used as adjective or adverb: * 10 is 2 more than 8 * He is more in sorrow than in anger.
The two examples are cited only to show that if you stick to the lexicon meaning of ###no more than, you'll land at this meaning of JUST as is said by King Lear's youngest daughter, ".....nor more, nor less", about her bond with her father suggesting only "just or equals to".