My reply: Do you mean "things that are done habitually" cannot be regarded as Habit? I am afraid you have an incorrect way of defining things. What will you call "I brush my teeth"? Is it a habit or a habitual action?
It can easily be both. Grammatically, in English, it tells us of habitual action.
To be fair, people do use 'habit' to explain Simple Present:
I use Habit to stand for those which grammars use to describe the use of Simple Present, like Habitual Action, Routine, General Truth, Repeated Action, Permanency, etc. Are you sure we must use only "habitual action" to refer to Simple Present, instead of all other callings? Or will you insist that Simple Present denotes only habitual action, but not routine, nor General Truth, not Permanency?
No, you're right. We use the present simple tense FORM for all those things you've mentioned [OR you mentioned].
Between Habit and Habitual Action, you are word-playing. If your sense of definition is that good, please try to define "present time". Maybe your wordplay is the best you can do to bypass its definition.
If you're so set on a definition, define it yourself and then show us how it is used in relation to the various tense FORMS.
Most important, our examples are referring to the same kind of examples, like "I brush my teeth". We just use a calling to refer to all such examples. Must they be called only "habitual action"?
No, noted above.
Actually, it is the sentence that expresses "habitual action, routine, or repeated action, or things that are done habitually". When the sentence denotes a Habit, various tenses also denote a habit, indicating different parts of time. If you have a habit "I brush my teeth", wouldn't Present Perfect "I have just brushed my teeth" be a habitual action also?
NO, ABSOLUTELY NOT! "I have just brushed my teeth" does NOT describe an habitual action.
Actually, it is the sentence that expresses a meaning. As in the quoted example from wikipedia.org above, since the author takes up a Simple Present sentence that expresses ability "I play the guitar", he adds that the tense expresses also ability. How can you deny the expression of ability? You can't, because Simple Present can "express" any meanings.
You're seizing on a mistake to buttress your position. There is nothing inherent in "I play the guitar" that tells us of any ability. If that were so we could do without 'can/good at/ proficient/etc.
The guitarist in question may well be terrible. All it tells us is that that person makes a habit of playing the guitar.
People have always confused a sentence with a tense. And this is why they cannot define "the present time". They include you, of course.
Did you notice a correspondent here and I had discussed and concluded we use past tense, rather than present tense, to say past habitual actions? Will you add any different opinion?
No, I didn't notice, Shun. If you'd like me to comment on that in particular then you'll have to quote the dialogue involved.
But there is nothing remarkable about that. Habitual actions can most certainly end and when they do, they are no longer habitual actions that can be described by the present simple tense FORM. So of course, it makes perfect sense that language would have a way to discuss past habitual actions.
When "He lives in Tokyo" is no longer the case, that habitual action/routine/general truth cannot continue to be described by "He lives in Tokyo", ie. the present simple tense FORM.
Now we can use, "He used to live in Tokyo" or even "He lived in Tokyo".