But it's not a question of "taking a role". It's a question of where your expertise is.

You should definitely have proper time lines, that has nothing to do with full stack developers.

Downtime? If downtime is an issue for your system, most likely you can build it so it can be live with some parts off and do maintainenance during working hours. (Redundancy, etc)

Integration and dB teams, imo, is an antipattern.

But what I really did not agree with with your original comment was that managers look for full stack devs because of cost.

I look for the right people, and I build my teams with a mix of frontend, backend and fullstack devs. It has nothing to do with cost, it has to do with building efficient and dependentless teams.