[saagarjha]

It's that Safari implemented support for it. Firefox added their own version and chose to give it a different affordance

[Y_Y]

> You keep using that word, I do not think it means what you think it means.

- Inigo Montoya

This is no affordance. There's nothing the design of either browser that suggests you can obtain a link preview by those actions, you just have to be told what action to take beforehand.

[saagarjha]

What part of long pressing a link is discoverable to you