Comment by abanana

Exactly. Ad creators know that the purpose of what they're building is more important than their personal dev experience of using shiny new tools. It's such a shame the fashion is the other way for so many web developers, largely the younger and less experienced ones.

And yes, it makes sense to use one particular old browser as a general proxy for older browsers in general, so people shouldn't get hung up on the particular version of Safari you happened to mention.