Strava's full OAuth scope gives apps access to every activity, friend, club and segment in your account. For a planning tool, that's overkill — and a privacy ask we weren't willing to make.
Strava BYO uses a narrow read-only flow scoped to your activity feed. We can pull what you ran without browsing your social graph or seeing private routes you haven't published.
The trade-off is a slightly slower onboarding for power users. The win is that your Strava data stays your Strava data — and we sleep better at night.