...or they just don't care about users space on devices, and say "how deep does the top 1% of users scroll?", multiply that by average video size, and set the cache at a level, that makes the app download every photo only once, even for "the worst" users.
I'm probably preaching to the choir, but when people run out of space (real or percieved), they sort by size to figure out what app to remove. Even if the user does cycle through many apps because they can't fit all the ones they want at the same time (and many do), there's always a chance that they don't come back. And, if they do come back, verification is a cost center. Either directly, through SMS or voice costs, or indirectly, through support needs as people invariably forget their password, or their email address, or their username or even their phone number.
But hey, if the big names don't want to deal with it, more room for smaller teams.
