I think you're missing the point. We're not comparing Safari with IE6 -- that would be absurd, we're just saying Safari compares to it's peers (Chrome, Firefox, heck, even Edge) like IE6 used to compare to the other browsers back in the day: stuff would mostly work on everything else but always needed special attention/polyfills/workarounds for IE.
On the project I currently work on the codebase is _littered_ with workarounds and hacks to get stuff to work on Safari.
> we're just saying Safari compares to it's peers (Chrome, Firefox, heck, even Edge) like IE6 used to compare to the other browsers back in the day <
Again, this is nonsense.
There is a gap, but it's not bending the shape of the web or costing the average developer hundreds of hours to work around bullshit. Safari is behind on some features... no doubt at all. But to compare that to IE 6 is just wrong.
On the project I currently work on the codebase is _littered_ with workarounds and hacks to get stuff to work on Safari.