@albertk836, “soft pull-ups” are available on the Photon but with a value of about 40K ohms, they are too “weak” for I2C. The underside of the Photon is bare of any parts specifically so it can be flush mounted using the castellated edges on a PCB.
Having built-in pull-ups is both convenient and cumbersome at the same time. Which voltage do they pull-up to? Most of the time, external shields and breakouts come with pull-ups so the Photon ones would need disabling. The I2C protocol is well defined and well understood. The issue is not that pull-ups are not included on the Photon. The real issue is that few board makers document their I2C implementation clearly stating whether or not they have implemented pull-ups or not and to what voltage.