Crucially, SO's election system needs to be bootstrapped: users aren't eligible to vote until they have a history of participation. The level of participation is fairly trivial, but it provides enough signal to allow a reasonable detection (and elimination) of bot / sock puppet networks without resorting to crude measures like blacklists or "bot tests".
For new sites, this meant that the bulk of moderation was done by employees, followed by employee-appointed temporary moderators. This dramatically reduced abuse, but also reduced the explosion of new sub-communities that sites like Reddit thrived on.
It was pretty decent in the mid and late 00s. The community started turning toxic in the very early 10s and by about 2015 was quite poisonous. The saddest part is that the problem was known and spoken about frequently, but the response to that from staff and/or high-level mods was to just double down and dig in.
For sure, advanced difficult topics were never really their forte', although it was really common to get great book or blog recommendations via comments. For me, the golden combination was a good book on the language/framework/topic I was stuyding, supplemented with specific Q&A from Stack Overflow. I have extremely fond memories learning C++ and Qt that way (although that Qt book was a little rough, but at least there was a Qt book. Nowadays every book just seems too outdated to be helpful).