If there are 7 billion people in the world, then 1% would be 70 million using bitcoin in some kind of way... Are we even close to that?
Obviously not. It would take about 280 days to make 70 million transactions on today's Bitcoin Core. Over a month on Bitcoin Cash, which is still too long, but nearly an order of magnitude better. Because big blocks.
... and because abnormal block production rate due to fickle difficulty adjusting mechanisms. Let's tell it all.
But I have a question for you, or whoever else may be able to answer:
I'm just trying to point out that there is at least one alternative method that a transaction originator can use to split their coins, which does not suffer these drawbacks.
(Namely, including coins from a post-fork transaction in the "splitting" transaction. Can't find jbreher's other post for a proper quote.)
Apart from a coinbase transaction, which outputs would qualify? In other words, can a simple guy set up such a splitting transaction without access to a freshly mined block?
Any descendant transaction would also be valid. An exchange could split all their coins once they have access to a single UTXO that is unique to one chain. There will likely be services (and exchanges) that accept a dual transaction to a single address (valid on both chains), and then either send you or credit your account with split coins.