- Current betaflight devevelopers and leaders are incompetent (They inherited the code base from others), and are slow, and varying degrees of willing, to add higher-level flight-control mechanics (semi-autonomous modes etc).

- The Ardupilot and PX4 configuration systems, and general experience, are user-hostile.

Note that the converses of these hold: Betaflight has a reasonably-good user experience, and Ardupilot and PX4 have extensive higher-level flight control mechanics. If only you could get the pros of both together!

Regarding hardware, frames generally accommodate flight controllers and ESCs elegantly, but other hardware like cameras, radios, and especially batteries, feel clumsy to assemble in a safe and consistent way.