The point is: don't do business on telegram.
Use telegram to contact folks, then carry your business out in some external platform. Use escrow or localbitcoins or something that maintains records.
Telegram isn't a trade app, it's a chat app.
A chat is supposed to lead you to a deal but not represent the deal itself. In real life do we just do deals based on chats or do we have contracts and actual papers? Why would online deals be any different?
The thing is that a lot of the times, this isn't applicable.
It's not always feasible to use an escrow in certain transactions, like giving out loans or whatnot, because the whole transaction is based on the receiver being able to access the funds now so that they can repay later.
Whilst it is questionable that this is allowed to happen at all on Telegram, I wouldn't say that it necessarily means that you need to avoid telegram for business dealings, especially when your contacts may already be established on that platform. Just make sure that you ask for a signed message, whether that be bitcoin/PGP/etc. and verify that signature before you agree to any deals, so that you can at least hold the counter party accountable.