This summary concisely captures the key thing about generics that has kept them out of Go for so long: they weren't created in a vacuum. Go's developers had the flaws in C++ and Java's approaches to draw on in their attempt to find a better approach. Many people calling for generics to have been implemented sooner were fine with those flaws in the other languages, but the Go team wanted to do better than that.
If they wanted to avoid problems they would have implemented the feature right away, instead of making it a second thought for a supposedly modern language.