[solardev]

Anecdotal perspective: As a user, I hate these third-party services because they can't make use of the built-in features of photo sharing apps that Google and Apple already make. You have to go through some pain in the ass individual (or bulk select) upload process, deal with a long-running thread in your browser (which may be interrupted and may or may not gracefully resume), etc.

vs like in Google Photos, you just hold-select a bunch of photos you already took (and probably auto-synced to the cloud), add them to the shared album... and done! No additional friction and no re-uploading needed.

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That said, I don't know if that's a common enough workflow for your average non-HN, non-power-user =/ It's possible people don't even know that feature exists.