[basementcat]

Screening at a theater is a required step before a film can be considered for certain prestigious industry awards, qualify for certain production tax incentives or fulfill cast/crew contractual requirements. There exist theaters the sole purpose of which are to fulfill that specific function (they generally screen low budget indie films each for a day or so-- it is not usual for the size of the audience to be zero).

Personally I don't really disagree with you; it would be great if good films were available on Amazon, Netflix, etc sooner.