Sure, testflight makes it easier (it's been around for years...). But you still have to invite people to testflight, after theyve signed up and added their device, you can provision the app for each device, after adding it to your developer account. Finally you can upload the build and have people install it. Obviously the process gets easier with time, and if you're not adding new people to the team.

But, with Android you build the APK and send out as an email attachment to whoever and you're done. Set up a shared directory on dropbox or google drive or w/e if you want.