Over the past one and a half years, Stack Overflow has lost around 50% of its traffic. This decline is similarly reflected in site usage, with approximately a 50% decrease in the number of questions and answers, as well as the number of votes these posts receive.
The charts below show the usage represented by a moving average of 49 days.
What happened?
https://en.m.wikipedia.org/wiki/Fediverse
Based on that, there is no “q&a” type of Fediverse software (a clear answer and a clear “voted best” answer).
Stack overflow had a huge number of “mod tools” to help curate the content (gold nuggets) given. They did not do the step of aggregating content (gold ingots) like Wikipedia has. The marking as duplicate could and should be tempered by “due diligence” or “age of the last time this was asked”, but how it is implemented is up to them.