That's exactly what this change is. You mean why wasn't it that way before the change? Maybe because it wasn't ever needed before? Git's been good with only sha-1 for 12 years. Think about the flip side of your question... what were the alternatives 12 years ago, or 5 years ago? And why would someone write code for alternatives that aren't expected to be used and maybe don't exist?
In my experience, generalizing ahead of need more often than not causes problems, and I've watched over-engineering result in far more effort to fix when the need it was anticipating does arrive than just waiting until the need is there.
In my experience, generalizing ahead of need more often than not causes problems, and I've watched over-engineering result in far more effort to fix when the need it was anticipating does arrive than just waiting until the need is there.