One of the possible reasons is that they want to wipe off this traditional crypto exchanges that are not fully regulated and controlled by Governments, and they want to push people into using platforms that they have full control of.
The Idea is to get people to abandon bitcoin which they can not also control and then trade those ETFs on exchanges that Governments can control and manipulate any time they want.
Your perspective on governments potentially aiming to steer users away from decentralized cryptocurrencies towards platforms they can regulate is thoughtful. It's obvious with the increasing regulatory scrutiny they're bringing, but from exchanges that have been compliant so far, they still try to give this decentralised vibe in how they have merged DEX features into the platform, like web3 swaps and the likes.
What cryptocurrency exchanges are there that you know are regulatory compliant? How certain can we be that the SEC won't go after them?