Some people are under the misconception that Sunnah and Fiqh are mutually exclusive. That is not the case. In fact, Fiqh explains the Qur'an and Sunnah to the lay people.
Those who call towards Qur'an and Sunnah do not really mean Qur'an and Sunnah, rather they mean to say Qur'an and Hadith. Because Sunnah itself is derived from Hadith and that derivation needs understanding. And that understanding is known as Fiqh.
Let me pose some simple questions to explain why it is a fallacy to call lay people to abandon Fiqh and follow just Qur'an and Hadith:
Allah :swt: says in the Qur'an:
أُحِلَّ لَكُمْ صَيْدُ الْبَحْرِ وَطَعَامُهُ مَتَاعًا لَّكُمْ وَلِلسَّيَّارَةِ ۖ وَحُرِّمَ عَلَيْكُمْ صَيْدُ الْبَرِّ مَا دُمْتُمْ حُرُمًا ۗ وَاتَّقُوا اللَّهَ الَّذِي إِلَيْهِ تُحْشَرُونَ
Lawful to you is game from the sea and its food as provision for you and the travelers, but forbidden to you is game from the land as long as you are in the state of ihram. And fear Allah to whom you will be gathered. [5:96]
It is normally understood from this Ayah that seafood is Halal for us. But we find several types of creatures in the sea, such as sea snakes,
tube worms,
Squids,
Jellyfish,
octopus,
seahorse,
sea pig, frogs, crocodile etc. Are these all supposed to be halal? If not, then what is the criteria for finding out what is Halal from sea creatures and what is not?
The fuqhaha have studied the relevant Ayaat and Ahadeeth and presented some guidelines for determining which of these creatures would be Halal.
At another place, Allah :swt: says:
ۚ وَإِذَا حَلَلْتُمْ فَاصْطَادُوا ۚ
... when you come out of ihram, then hunt. [5:2]
Can anyone say how important it is for a person to go hunting after coming out of ihram? Is it Fardh? because Allah :swt: is commanding it. Or is it Wajib or Sunnah or Nafl?
Now for a few examples from Hadith:
عَنْ عَائِشَةَ، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ كَانَ إِذَا افْتَتَحَ الصَّلاَةَ قَالَ " سُبْحَانَكَ اللَّهُمَّ وَبِحَمْدِكَ تَبَارَكَ اسْمُكَ وَتَعَالَى جَدُّكَ وَلاَ إِلَهَ غَيْرُكَ " .
It was narrated from ‘Aishah :raha: that when the Prophet :saws: started Salat he would say:
“
Subhanak Allahumma wa bi hamdika, wa tabarakas- muka wa ta’ala jadduka, wa la ilaha ghayruk (Glory and praise is to You, O Allah, blessed is Your Name and exalted is Your majesty, none has the right to be worshipped but You).” [
Ibn Majah]
What is the ruling for reciting the above at the start of prayer, is it Fardh, Wajib, Sunnah or Nafl?
If someone forgets to recite this, then does he have to repeat his whole prayer? Or does he have to perform Sajdah Sahw? Or he doesn't have to do anything and his prayer will be valid?
Another example:
عَنِ ابْنِ عَبَّاسٍ، قَالَ تَوَضَّأَ النَّبِيُّ صلى الله عليه وسلم مَرَّةً مَرَّةً.
Narrated Ibn `Abbas :ra::
The Prophet :saws: performed ablution by washing the body parts only once. [
Bukhari]
عَنْ عَبْدِ اللَّهِ بْنِ زَيْدٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم تَوَضَّأَ مَرَّتَيْنِ مَرَّتَيْنِ.
Narrated `Abdullah bin Zaid :ra::
The Prophet :saws: performed ablution by washing the body parts twice. [
Bukhari]
عَنِ ابْنِ شِهَابٍ، أَنَّ عَطَاءَ بْنَ يَزِيدَ، أَخْبَرَهُ أَنَّ حُمْرَانَ مَوْلَى عُثْمَانَ أَخْبَرَهُ أَنَّهُ، رَأَى عُثْمَانَ بْنَ عَفَّانَ دَعَا بِإِنَاءٍ، فَأَفْرَغَ عَلَى كَفَّيْهِ ثَلاَثَ مِرَارٍ فَغَسَلَهُمَا، ثُمَّ أَدْخَلَ يَمِينَهُ فِي الإِنَاءِ فَمَضْمَضَ، وَاسْتَنْشَقَ، ثُمَّ غَسَلَ وَجْهَهُ ثَلاَثًا، وَيَدَيْهِ إِلَى الْمِرْفَقَيْنِ ثَلاَثَ مِرَارٍ، ثُمَّ مَسَحَ بِرَأْسِهِ، ثُمَّ غَسَلَ رِجْلَيْهِ ثَلاَثَ مِرَارٍ إِلَى الْكَعْبَيْنِ، ثُمَّ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ تَوَضَّأَ نَحْوَ وُضُوئِي هَذَا، ثُمَّ صَلَّى رَكْعَتَيْنِ، لاَ يُحَدِّثُ فِيهِمَا نَفْسَهُ، غُفِرَ لَهُ مَا تَقَدَّمَ مِنْ ذَنْبِهِ ".
Narrated Humran :rh:, (the slave of 'Uthman :ra

I saw 'Uthman bin 'Affan :ra: asking for a tumbler of water (and when it was brought) he poured water over his hands and washed them
thrice and then put his right hand in the water container and rinsed his mouth, washed his nose by putting water in it and then blowing it out. then he washed his face and forearms up to the elbows
thrice, passed his wet hands over his head and washed his feet up to the ankles
thrice. Then he said, "Allah's Messenger :saws: said '
If anyone performs ablution like that of mine and offers a two-rak'at prayer during which he does not think of anything else (not related to the present prayer) then his past sins will be forgiven.' " [
Bukhari]
All these are from Sahih Bukhari. Can a layman read these Ahadeeth and determine the Sunnah method of performing wudhu, is it washing the limbs once, or twice or thrice?
You will find several such examples in the Qur'an and Hadith where you will need to follow the guidelines shown by the Fuqaha to understand them properly. Otherwise, simply reading an Ayah or Hadith will cause confusion and there is a big chance of a person being misguided and led into
waswasa.
That is why the scholars of the past would say:
Hadith are a pitfall except for the Fuqaha’.
Imam Ibn Abi Zayd al-Qayrawani al-Maliki رحمه الله narrated that Imam Sufyan ibn Uyaynah رحمه الله said:
“ Hadith are a pitfall except for the Fuqaha’ –> {Legal Jurists},”
Imam Malik’s رحمه الله student and friend `Abd Allah ibn Wahb رحمه الله said:
“The meaning of every Hadith is a pitfall except for the Ulamah {scholars}, means that everyone who memorizes Hadith that does not have an Imam in Fiqh {Law} is misguided, and if Allah had not rescued us with Imam Malik and al-Layth, we would have been misguided.”
...
Imam ash-Shafi’i رحمه الله said: “You –> {the scholars of Hadith} are the pharmacists but we {the jurists} are the physicians.”
Mullah Ali al-Qari رحمه الله commented on this and said:
“The early scholars said:
The Hadith scholar without knowledge of Fiqh is like a seller of drugs who is no physician: he has them but he does not know what to do with them; and the Fiqh scholar without knowledge of Hadith is like a physician without drugs: he knows what constitutes a remedy, but does not have it available.”
Source: http://www.muwatta.com/the-hadith-scholar-without-knowledge-of-fiqh/