lol.
you do know why something deemed "backward compatible" is not simply activated instantly.
after all if really backward compatible. its just as valid now as ever right... (but read the small print and you see the holes)

you do know even when activated core wont have a walet enabled release for people straight away...

you do know why segwit needs to be upstream filters and actively ban other non-segwit nodes from being upstream. this includes banning pools and their non segwit blocks from being added on after.

you do know why segwit will not relay segwit unconfirmed tx's to non-segwit nodes.

not only that but the sigop quadratic spamming is not solved due to it not stopping native tx's
the malleability is not solved because it does not stop native tx's

the tx count wont reach expectations because it does not stop native tx's

once you look passed the scripted half promises. and look at how it works.. you see the promises are empty.
you also start to see new attack methods aswell as the old ones that still exist.

also.
litecoin transactions have been fully running and used for 6 years. all tested by thousands of people..
.. but introduce them onto bitcoins mainnet. no one knows what will happen.

and segwit transactions are the same 'many tests and been running on alternative networks for x month' but never on bitcoins mainnet..

(some attacks have been highlighted. even i highlighted the main one last year, which led to the whole ordeal of not releasing the segwit key wallet until way after activation. but even then there are still attack vectors that can and will happen with segwit tx's and native nodes after activation).
hint: though segwit nodes mess with ban lists and not auto relaying unconfirms to native nodes.. some script kiddie can manually copy the segwit mempool and push segwit unconfirms into their native nodes mempool and have a nice play around.