What's with Mid laners not roaming?

It isn't as easy for mages to really roam this season unless you are an Assassin Mage or an AD assassin that can for sure get a kill because the AP items are so much more expensive now that if a mage leaves lane and nothing happens then they just lost out on A LOT of gold and exp therefore putting them behind drastically. Now i understand if you mean a FED mid laner not roaming then idk what to tell you, but for the most part that is why a lot of mid laners probably won't roam as much right now.