Adapted from a discussion on whether Muslims should simply identify as Muslims rather than follow a madhhab (school of law).
Let's ask a different question:
Would you go to a doctor who refused to tell anyone what university they studied medicine at?
You, as a person in need of a doctor, don't need to identify as a graduate of Harvard medical school or John Hopkins or any other medical school.
However, you surely want evidence that your doctor has studied medicine in a systematic fashion so you can trust his prescriptions.
Din is the same way. As a layman, you don't need to identify as following "Harvard's medical curriculum" or a particular madh'hab. But when you need a ruling, you want to make sure the person giving it is properly licensed to do so. In Islamic law, the institutions that properly license someone are the madhahib.
If you decide you want to actually study in a serious way, you don't go and take 101 level courses at 4 universities. Someone who is a freshman at 4 different schools doesn't get a degree. You pick one school and continue until you get a bachelor's, master's, or PhD.
Similarly, when you are ready to take fiqh more seriously, you pick a madh'hab and study it.
The madhahib are not personalities or sects or identifiers, and some extremists do take them as such. They are schools to systematically study law.
If you felt very ill, would you trust yourself to conduct independent online research to treat yourself? Or your parents? Or your children?
Or would you rather have a qualified doctor take a look?
That's the same thing with Islamic rulings and evidence. The layman can spend all day researching Quran & hadith online, just like you can look up pharmaceuticals & research papers. That will never replace 8 years of university plus residency to become an actual MD. Similarly, online research of Islamic sources will never replace an 8 year alim program plus independent scholarly study.
This began as a comment I wrote on Reddit. Read it in context here: https://www.reddit.com/r/islam/comments/1w9158g/why_cant_we_just_identify_as_muslims_instead_of/p87uam2/