What is preventing exchanges/platforms from deploying Lightning Network now?

No offense intended.

In my opinion, LN can temporarily solve the so-called scaling problem if it really works as good as it claims. Yet why nearly no exchanges/platforms have deployed it?

It seems that crypto exchanges can simply open channels with each other, then their users can transfer btc between exchanges for less than 1 cent. No need to "find a route and pay additional fee". Technically, if they set up the channels cleverly, then it won't need to be closed in a very long time, if not forever.

So the deployment will improve user experience so much.

Yet why nearly all exchanges/platforms haven't deployed it?

Thanks.