What is the quickest way to cut to the chase?

For starters, all Muslims should fire their respective sect leaders and then follow it up with denouncing all sects. Islam is what the Quran says it is and pointing this all-important fact does not make anybody a Quranist, whatever that means.

To cut to the chase, the logic is simple and clearly laid out in the official message of God in no uncertain terms; the sects want to impose their own laws on people, God on the other hand categorically forbid believers from Judging (يحكم) by anything other than what was Revealed (أنزل). To ensure that whatever was Revealed was actually delivered publicly, God instructs the messenger to do exactly that (بلغ) announce/convey/proclaim/deliver the Revealed (أنزل) message. Whatever was not publicly conveyed and declared as a Revelations by the messenger should not be taken as a basis for judging because doing so will render one as a disbeliever (كافر).

Hence, there may or may not be communication between God and His Prophets other than the official message like the Quran or for that matter with ordinary human beings. In fact, Quran is clear that God communicates with all His creations even innate objects like heavenly bodies like the Earth.

The Wahi that is intended as a guide or injunctions for us as human beings are in fact clearly defined in the Quran and must be delivered publicly by the messenger.

Here are the relevant verses;

Indeed, We sent down the Torah, in which was guidance and light. The prophets who submitted [to Allah] judged by it for the Jews, as did the rabbis and scholars by that with which they were entrusted of the Scripture of Allah, and they were witnesses thereto. So do not fear the people but fear Me, and do not exchange My verses for a small price. And whoever does not judge by what Allah has revealed then it is those who are the disbelievers. Quran 5:44

and

O Messenger, announce (بَلِّغْ) that which has been revealed to you from your Lord, and if you do not, then you have not conveyed His message. And Allah will protect you from the people. Indeed, Allah does not guide the disbelieving people. Quran 5:67

To further elaborate on this all-important issue, in order for it to be classified as a Revelation, it is necessary for it to be announced, a public act by definition as demonstrated by the use of the word (بَلِّغْ) and the context elsewhere in the Quran. Quran 7:61-62. and 7:67-68 and 46:23. And this announcement must be done by the messenger himself and declare it to be a Wahi for it to become part and parcel of the official message. Certainly not left to a third party (s) to deduce from his actions or inactions.

In order to settle the matter of a public announcement in the above verse, God comforts the Prophet of God that not to worry about the public declaration of the Revelation to the people because God will protect you from the people. The mention of the people here and all the related verses buries assigning any value to a single narrator, that will be 99.9% of Hadith literature, actual number. Especially negates any claim where it was communicated in private. In addition, a single narrator's claim that it was made in Public is by definition problematic. Interestingly, 100% of the so-called Qudsi Ahadith falls into this latter category. Furthermore, there is no provision for implied or deduced Revelation on the basis of not able to come up with an "explanation" for a particular verse. Nor declaring something other than the officially revealed as "additional Revelations" under the disguise of "explanations"  has any merit.

Why is this extremely important? Because if one were to use anything other than the Revealed word of God, as defined in the Quran, to judge others then in God's own words as pointed out in the above verse;

" ........ And whoever does not judge by what Allah has revealed then it is those who are the disbelievers". Quran 5:44

Imagine that !!!

That automatically takes care of what Obey the messenger means. In fact not making the Revelation as the sole basis of a Sharia is not an option, in fact, if one were to venture out and actually judge others on anything other than the Revealed message then that will turn one into a disbeliever as the verse above declares. The seriousness of the issue is further cemented in the subsequent verses by adding wrongdoers and defiantly disobedient to the mix. This was true of those who received Revelations before us and it is the same for us.

Please read and reflect on the verses from Quran 5:44 till 5:69 to fully understand the fundamental principles of Revelations.

Of course, there are many more relevant verses but the above is a very quick way of settling the counterclaims of the sect scene.