It's not about a person's level of formal education, it's about whether you have educated yourself on this particular topic. I believe there is a very big difference between making an informed decision to wean early and an uninformed decision to wean early. I knew the guidance was to wait 6 months and the reasons behind that, and informed myself of the many possible signs of readiness. I started with the intention of waiting to 26 weeks but ended up weaning at 22 weeks as I had became aware over a period of weeks that my DS was probably ready. He took to feeding himself and eating without a problem straight away.
Compare this to my friend who weaned her DS at 16 weeks "because milk wasn't enough for him as he's a big boy".
We both went to the same university, same class of degree, same type of job etc. It clearly isn't about education but it is about being educated or educating yourself about not weaning early. So many of the people who wean early do so from an uninformed, uneducated position. They are not interested in / don't have the time to do 'independent' reading and research so they will get their advice from their parents (who were in a wean early culture), from a HV (many of whom advocate weaning at 4 months and don't have the time or the inclination to explain why we should wait) or from the jars they see in the supermarkets which 4 months plus on the front and then have some smallprint gobbledegook on the back about how it is better to wait until 6 months.
So people take this advice as meaning it is probably okay to wean even earlier than 4 months if they have a big baby / baby waking up at night / baby needing feeds more than every 4 hours etc.
If jars said 6 months + rather than 4 months +, then people would still wean early because they have a big baby / wakeful baby / frequent feeding baby but perhaps many of them would wait until 4 or 5 months rather than the heartbreakingly early 2 or 3 months now.