The Nokia 8 comes with a top-mounted 3.5mm headphone jack. We can clearly that unlike its competitors (Apple, I am looking at you), Nokia has decided not to follow the latest trend of removing the headphone jack. This means users can still use their current 3.5mm headphones without any adapter, just plugging in the earphone/headphone to the 3.5mm headphone socket and enjoy listening to music, as they were used to for many years. The Nokia 8 has a USB-C connector at the bottom for charging your phone. In phones like iPhone 7, you don't have a 3.5mm headphone jack, and your only options are either to buy a USB Type-C headphone or buy an adapter to connect your current 3.5mm-compatible headphone.
I believe that eventually most phone manufacturer will drop support for this "ancient" port, but Nokia probably believes that is just too early to do so. I personally don't know when it will be the right time to do it? Maybe once USB Type-C headphone will become as the 3.5mm ones. The thing is that they would become more popular once most phones will support USB-C connectors and drop the 3.5mm support. This what Apple is trying to do. Apple is definitely have a huge role in dictating the trends in the mobile market. I guess the market is not cooked enough for dropping the 3.5mm socket and it might take a few years more until the 3.5mm will be dropped almost completely in favor of the USB-C port.
I also like the choice of putting the 3.5mm headphone jack at the top of the phone, rather than the bottom (yep, some phone manufacturers do that). I personally prefer the top position because it's more convenient for me when I hold the phone in my hand where my palm covers the bottom of the phone.