What are the risks of over-relying on side-by-side extensions?

Building too much logic as separate side-by-side applications, even when simpler in-app extensibility would have sufficed, introduces its own accumulating architectural costs that mirror (in a different form) the technical debt Clean Core is meant to avoid on the core system.

• Integration sprawl — many separate applications each maintaining their own connection back to the core, multiplying the surface area for integration failures.
• Operational overhead — each extension is its own deployable application requiring monitoring, patching, and lifecycle management, multiplying operational burden as extension count grows.
• Fragmented user experience — business processes that span multiple separately-built extensions can end up feeling disjointed if not deliberately designed for consistency.
• Cost — running many separate BTP applications has real infrastructure and licensing cost implications that can exceed what simpler in-app extensibility would have required.

The lesson is that "clean" doesn't automatically mean "side-by-side by default" — over-applying it just moves complexity from one place (the core) to another (a sprawling extension landscape) rather than genuinely reducing it.