Humans are producing so much content right now in the form of software, art, movies, writing. Does it really matter if we leave some behind? Do we need to preserve every piece of information we generate?
I have software on the App Store that I cherish that unfortunately will never be updated past 32 bit (too much work). But I don't care, nor do I feel the need to preserve it.
You say there is no benefit to this move. But this move significantly reduces Apple's technical debt and support requirements and is likely to be worth the tradeoff for future developers and future software on the platform.