Motivation
So on EL&U, I pretty often encounter the claim, under a question of some usage or other, that certain usages are the consequence of "lazy speakers", who "would otherwise" use some (fuller, more complex, more difficult to pronounce, longer, whatever) construction, but in order to save effort or energy, they use a (shorter, simpler, elided, contracted, phonetically compressed, whatever) construction.
Theorem
That is, I am asking about theories that these (typically) native speakers know what the proper thing to say is, but consciously choose to say something else because it's "easier to pronounce". This is not attributed to their dialect or sociolect or some other group-level account, but to individual speakers saving energy or effort.
Examples
Two recent questions on EL&U where this theory was raised spring to mind.
The first exchange was under question related to the usage of whom, where the relevant part of the comment chain between a commentator (C1) and myself (M) went:
[C1] Some say that the virtual demise of "whom" is yet another example of the 'dumbing-down' of the language, and that it's no wonder the French think we're nits (or is it nuts?)
[M] Pretty sure people have been caviling about the "dumbing-down" of English since Chaucer, or before. It's a perennial myth. As for the French, which is more nuts, accepting the world is what it is, or trying to legislate evolution?
[C1] What's evolution got to do with it? It's lazy speech, simple as that.
The more recent exchange (with a different party, C2) was under a question by a non-native speaker asking about the idiomaticity of explain me vs explain to me.
[C2] Consider that most people are lazy in their speech, but some lazier than others. It takes considerable effort to say "Explain to me ...", but is much easier (and more natural sounding) to say "Explain tuh me ..." From there it's just a short step to "Explain duh me ..." or "Explain t'me ..." The "duh" or "t'" sound is very easy to say and very easy to shorten almost (but not quite) into nonexistence. It's actually harder to say "Explain me" than it is to say "Explain d'me", so it's rare that the remnants of "to" are completely eliminated, just chopped down to near nothingness.
[M] This concept that there exist "lazy speakers" has apparently gone viral; the pathogen is spreading out of control. People who say "explain me" are not taking shortcuts; they're taking the wrong path, misled by signs in their own language. If there are native speakers who use it in their dialect, it is just that: their dialect. Not "lazy".
[C2] You miss the point. They feel that they are saying "Explain to me", they're just not making an effort to enunciate clearly.
Now, to be clear, I don't find it implausible that this has happened at some point in time.
I am skeptical that "lazy speech" can be used as an account for a regular pattern of speech, where the non-native OP can expect to meet, in his life, some meaningful number of native speakers who drop the "to" consistently because they are "speaking lazily".
Question
I am, to put it mildly, skeptical of such accounts for usages.
My instinct, as a non-linguist, is that if a native speaker uses some pattern at odds with the standard or prestige dialect, it is almost certainly part of their local dialect or sociolect; it's not an individual conscious or unconscious decision to conserve energy or streamline phonotactics: they are simply imitating the speech to which they've been exposed.
Similarly, I don't find it sensible to describe a speaker substituting who where whom would have been used a decade before they were born as lazy, simply they haven't encountered "whom" in those contexts, so they haven't been trained to use it so.
Am I off the mark? What is the general disposition of the linguistic community towards the concept of "lazy speech"?
Are there established linguistic theories which or at least prominent linguists who incorporate "laziness" of individual speakers as a feature?
In other words, is "lazy speech" a thing?