Because parts manufacturers want you to believe that things are incompatible so that you continue buying the specific expensive chains etc.
I've been using a Sram flat top chain with a Shimano 11 speed groupset for 5000km and it is running sweet still.
It's fine.
Thanks for that info, interesting to know. Probably a marketing thing with little differences (also I thought when I first saw the flat top chains coming out "wow are they making chains now which are easier to produce" – even if there's more material to be sold)
Because parts manufacturers want you to believe that things are incompatible so that you continue buying the specific expensive chains etc.
I've been using a Sram flat top chain with a Shimano 11 speed groupset for 5000km and it is running sweet still.
It's fine.