Does anyone know if theres a particular reason that I must activate my invitation with the mobile app in order to use Inbox on the web? I was looking forward to

Does anyone know if theres a particular reason that I must activate my invitation with the mobile app in order to use Inbox on the web? I was looking forward to trying it out but its incompatible with all of my devices. Is Google just trying to push people with invites to try out the mobile application or is there some technical reason behind it?