What stops BCH chain from being used to transfer USDT or like this: The exchanges' users can move crypto coins in or out through different chains rather than the native chain.

When I tried to move some Crypto, it let me choose which chain to use. I made the decision upon the estimated fee.

One week ago, I thought that BCH was not competitive in terms of transaction fees compared to many other centralized chains. I thought that "the combination of fee + decentralization", rather than "fee", was the advantage of BCH chain.

Yet, I have changed my opinion because I didn't consider the subsidy which is block reward. With the subsidy, the transfer fee can be zero. What stops it from being zero is the risk of spamming.

So, as for BCH, the transfer fee itself is an advantage. It has one of the lowest possible transaction fees now and in the foreseeable future.

1 satoshi per byte means less than 0.1 cent for a normal transaction, which is much lower than the lowest option I saw on the exchanges.

So, why is there no infrastructure to let exchanges's users or other users transfer USDT and other coins on BCH chain? Why is BCH not an option? BCH has had smart contracts for more than one year.

What is even worse is that why the transfer fee for users to transfer BCH on BCH chain is more than 0.0002 BCH on many exchanges?

It makes no sense for people to pay more than 1 satoshi per byte on BCH chain given that the blocks are far from full both now and in the foreseeable future.

Is it because it is deliberately targeted by many exchanges or service providers?

If those guys are so obsessed with l2s, BCH can be the l2 for Bitcoin/Ethereum and any others. People can transfer wrapped btc/eth and other crypto on BCH chain. What stops this from being the reality?