There's a reason in tech we call the Internet of Things the Internet of Shit, putting your devices online tends to turn into a mess.
Stern isn't a big company, they're a little pinball shop. They don't know anything more about putting their game online than the people making 'smart' TVs or toasters, the things that are constantly having stupid headline issues.
There's the added cost of the hardware, the need to maintain the infrastructure and security, it's not just throw a switch, game updates itself. And you're going to do what? Pair your phone with your pinball to access features? Painfully enter your wifi password with the buttons inside the coin door? Get frustrated when your router gives your pin an IPV6 instead of IPV4 address and nothing works?
Just sounds like giant headache and something that will raise costs. And for what? Stern isn't exactly rolling out the weekly code updates.
Leaderboards to virtually compete are always going to be stupid, because someone will always cheat. And it's not like you have to work hard to cheat. And yes, it's stupid, and no, it doesn't matter, because people will do it anyways.