was it ever relevant?
The term was taken from print design and production at a time when the web was still fairly new and the only way to access it was through a desktop device. Most screen sizes were fairly similar and you could predict fairly well what something would look like.
Nevertheless, it was still an arbitrary term that allowed designers and content managers to sell shit into their stakeholders and clients.
Now we can access the web through a plethora of devices with a multitude of screen sizes and resolutions, "the fold" is even more defunct then when the silly term first arised.
Design for your user and their needs, not for a technical constraint you may never encounter.