What you are referring to are general provisions. These general provisions would usually apply, but as per the rules of statutory interpretation, if a regulation addresses a specific circumstance, then it will take precedence over the general provision.
As per the original post the OP had the issue wherein, he reentered Canada while the DS was valid. The OP was admitted into Canada, and therefore the conditions of Regulation 190(3)(f) would trigger, "(ii) return to Canada by the end of the period initially authorised for their stay or any extension to it"
This regulation referred under R 190(3)(f) is for, Visa exemption — purpose of entry
(3) A foreign national is exempt from the requirement to obtain a temporary resident visa if they are seeking to enter and remain in Canada solely
(ii) return to Canada by the end of the period initially authorised for their stay or any extension to it"
At the port of entry, if a returning visitor, who was previously admitted and is still in DS, would be admitted into Canada for the same DS as originally granted if they only visited US or St Pierre and Miquelon. When a returning visitor falls under this category, they will not even be assessed for a visa requirement, given that they squarely fall within the regulation.
The DS expired when the VR expired, and thus the OP has to either leave Canada, or apply for an extension (will be on implied status until a decision is made in accordance with R183(5)).
This is why IRCC's response states that person in Canada is without valid status because OP was only admitted into Canada until "the end of the period initially authorised for their stay or any extension to it."
This is my understanding of the facts and the law, based on what OP's post suggested. However, in general circumstances, the re-entry would trigger a 6 months stay, unless specifically enforced in the passport.
Had the OP visited another country, other than the US, then the general provisions would have applied. Also, the visa exemption nearly signifies that an applicant can re-enter Canada on a expired visa, given that they are in Status (eg. an applicant entering Canada on a 5 year student visa continues to remain in status until another 8 years. Even though the visa is expired, the study permit is current, and when returning from US, the applicant will not be asked for anew visa, rather the study permit will be enough for re-entry).
Further,
- In none of my posts have I ever mentioned that VR is a document based on which one can enter Canada.
- regulation 190(3)(f) does not refer to specifically study and work permits, it refers to TRVs. It also does not refer to exemption from documents, which is covered in R190(2).