Are you trying to tell us to store our funds(Bitcoins) on exchanges? Because that's the only way I know you can convert Bitcoin to usdt. Except you want to use multi coin wallets like trust which I still see as unsafe and not reliable. Yes the transaction fees is a very terrible thing at the moment but we shouldn't let a short time issue create for us a long time wound( something we will remember for ever).
Don't store your Bitcoins on exchanges. If at all, not all of them. You can just keep a small amount of funds there just Incase of emergency especially in times when fees are very high. Its a method that might save you fees but you may end up losing your funds through such method.
Trust wallet isn't the only custodial wallet with muti chain feature, there are many of them but Trust wallet is closed source when I checked and because of that, you don't really know the structure and how it's been designed as a client or to detect if there is a bug.
The OP is not saying we should used centralized exchanges but recommending one if at all the receiver would want to later send it to an exchange to convert to fiat. Sending Bitcoin from wallet to wallet will cost more since mempool is unstable, sending usdt will save the sender some transactions fees and the receiver doesn't have to bother to send to centralized exchange especially if it's not intra exchange.
However, this is not the best way to go about it. Segwit provide the lowest transaction fee as possible for Bitcoin transaction, a single input and output with effective fee rate of 22 sats wouldn't cost much. It's better to use that for high privacy.