Actually this brings up one of the things I like the most about this SO for Teams idea - it could also be used as a sort of slant.co substitute, where a large dev team is trying to settle on a common programming language or persistence framework, and each person can register their opinion or vote on an existing one.
After N days, the whole group decides to select the option with the most votes. Since voting is anonymous, everyone can give their honest opinion, or even vote for multiple.
If you don't like the "opinion-based" close reason, you can just not use it on your team.
It was a weak joke concerning the usual complaints about SO and because I thought it was an on-premise offer, not integrated in the main SO site. As said below, there's no flagging in SO Teams.
If you need anonymous voting for decision concerning language/framework, I think you have a big problem: it would mean individuals are afraid of voicing their opinions regarding a technical choice and that's not something that can just be solved with a tool.
After N days, the whole group decides to select the option with the most votes. Since voting is anonymous, everyone can give their honest opinion, or even vote for multiple.
If you don't like the "opinion-based" close reason, you can just not use it on your team.