Splitting a sequence using a binary predicate on adjacent elements

[Nordlöw]

On Wednesday, 18 October 2017 at 07:01:19 UTC, Andrea Fontana 
wrote:
> If you try to use your data with chunkBy!"a != b+1", it does 
> not work, as expected.

What's the motivation behind this limitation?

Without it

     chunkBy!"a + 1 == b"

is exactly what I want.