Shockingly, "get rich quick" schemes are a bad idea. Who would have thought? Oh, wait. Everyone.
I still think most cryptocurrencies should be highly legislated, because most adults in society are more or less children who can't be trusted around shiny objects, but we should really stop pretending the problem is with the technology. It's with the users, trying to shoehorn it into a use-case it's unsuited for (get rich quick schemes).
The context here is an exchange limiting withdrawals, so... Yes, exactly?
Decentralised exchanges have massive fees in practice. If you want to buy in and cash out after a year, sure. But show me one that takes <0.1% for the whole transaction including transfer/signing fees and supports BTC.
That said, I do know a decentralized exchange that fits your criteria. I'm not going to mention it, because I refuse to enable such incredibly harmful behavior.
I still think we should legislate it, but let's be honest: Most people who lose, here, kind of deserve it, for not doing the bare minimum of research.