Creating software is about making the right decisions at the right point in time. Any decision by nature restricts choice. It is precisely the job of CTOs and architects to make decisions about partners, platforms, tooling and frameworks and to refrain from making these decisions at other times.

Should you empower teams to make their stack choices? I've seen chaos breaking out for a year in a major development organization with 500 devs when most teams suddenly were allowed to make some choices that better should have been made centrally. Yes, they were faster but they were faster going nowhere. And then there are all these aspects that go beyond the development phase - long term maintenance, behavior of software in the field / training field engineers and moving people across teams.

Good technical leaders know where choice is called for and where not. Managing these trade-offs requires a perspective that goes beyond the agile team.