You also now want the current login severs to continue to support the old game logins and handle auth for them? So we're still supporting the old game, still maintaining it.

These old unmaintained, unmanaged servers you want to run get hacked they distribute malware to your users. Whoops, the hosting provider finds out, the business account gets locked, now nothing works.

They get hacked a different way, they start mining bitcoin, your hosting provider finds out and locks the business account, whoops, now nothing works.

They get hacked a different way, they intercept the api calls to the auth servers. They use the auth tokens to break into people's main accounts, use that for phishing attacks, steal millions of dollars. Whoops.

>it's not difficult to do.

That's the point you don't get. It is difficult. Standards change, security changes, things NEED updating or things go wrong, people lose confidence in you, you dont make any money and you go out of business.

Spin up an old version of minecaft on an old version of Linux, see how long it lasts before it all goes wrong.