The software architecture is a map of the organizational chart. If two teams don't talk, their services won't integrate smoothly.
Then
If you want a modular architecture, create modular, independent teams first. Do not fight the org chart with code.
Unless
Inverse Conway Maneuver
The architecture is downstream of the communication structure, not the org chart on paper — the one that describes who actually talks to whom. Redraw the teams and the seam moves with them; redraw the diagram alone and the old seam grows back.