exactly. So, even to understand verse 3:7, we shouldn't build our understanding based on wishful thinking. We need to see how those who were well-grounded in knowledge understood this verse. For that you would need to research their hadithes. Usually requires knowing some arabic though, as most hadithes are not translated yet. But what matters, in 3:7, is the Taweel, not Tafseer that is the subject.
I've read many hadiths on this directly or indirectly. For example in Tuhafaqul uqool, the letter of Imam Ali Al-Hadi (10th Imam) was explaining to his best capacity to a person about God's will with respect to guiding and misguiding, but at the end, said as far as it's unclear to seek refuge to God and leave it till it becomes clear, and said "those who follow the best of it" refers to those who follow the clear signs.
There is ahadith that say the Imams have knowledge of all the book and support it with different verses, among them "Nay, it is a clear signs in the hearts of those given knowledge" to be about them specifically, and that this verse verifies there is a people who the whole book is all clear signs to them. And we have hadiths that no one can recite or gather whole Quran but Imams, it's seen in this light, as the true recitation is often seen as the true way God intended, while Taweel in our hadiths is additional meanings and purposes. Tanzil (revelation) or recitation is again the true way God intended the Quran to be read and seen with respect to what the words mean in the Surah, while Taweel refers to deep layered meanings and additional signs you can derive from it.
Other hadiths say "mutashibhat" refers to their enemies and "muhkamat" refers to them. That is unclearness from Quran will lead to enemies of Ahlulbayt (as) because people interpret per their desires to say whatever they want, while the clear signs leads to Ahlulbayt (as) and manifests them.
There is also the fact, the Satan and his forces, cast sorcery with respect to every wish of a Prophet or Messenger.
[22:52] Never did We send a messenger or a prophet before thee, but, when he framed a desire, Satan cast with regards to his desire: but Allah will cancel anything that Satan casts regarding (it), and Allah will confirm (and establish) His Signs: for Allah is full of Knowledge and Wisdom. (partially from Yusufali, I adjusted the translation)
لِيَجْعَلَ مَا يُلْقِي الشَّيْطَانُ فِتْنَةً لِلَّذِينَ فِي قُلُوبِهِمْ مَرَضٌ وَالْقَاسِيَةِ قُلُوبُهُمْ ۗ وَإِنَّ الظَّالِمِينَ لَفِي شِقَاقٍ بَعِيدٍ {53}
[22:53] That He may make the suggestions thrown in by Satan, but a trial for those in whose hearts is a disease and who are hardened of heart: verily the oppressors are in a schism far (from the Truth):
وَلِيَعْلَمَ الَّذِينَ أُوتُوا الْعِلْمَ أَنَّهُ الْحَقُّ مِنْ رَبِّكَ فَيُؤْمِنُوا بِهِ فَتُخْبِتَ لَهُ قُلُوبُهُمْ ۗ وَإِنَّ اللَّهَ لَهَادِ الَّذِينَ آمَنُوا إِلَىٰ صِرَاطٍ مُسْتَقِيمٍ {54}
[Yusufali 22:54] And that those on whom knowledge has been bestowed may learn that the (Qur'an) is the Truth from thy Lord, and that they may believe therein, and their hearts may be made humbly (open) to it: for verily Allah is the Guide of those who believe, to the Straight Way.
Here 22:54 goes back to the possessors of understanding, as only they remember through the Quran. No one else really does see the clear signs and recitation.
We can see another dimension to 3:7, it's not just personal bias, for that can't account for the blindness to the household of Mohamad in Quran. It's actually, sorcery from Iblis and his forces, but then God says he will support the clear signs and prove them.
It's due to the fact, that God has uncast through the sayings of the Prophet, Fatima, and Twelve Imams, the misconceptions of Quran over all, and indirectly opened ways to uncast all that Iblis cast, that, the proof is complete. This is part of the reason why God was only pleased with Islam when the Wilayah of Ali (as) and his family was guaranteed to be conveyed through the generations at Ghadeer.
There is also a hadith Qudsi we have that names all Twelve Imams, but starts with the words from God "he doesn't believe in me who interprets my book per their caprice"