> What exactly is the point?

Something like: "We are better with closer ties and connections to the European Union. Brexit furthers us from them."

> countries have exchanged information [...] before the EU

This is true but quite a simplification. I don't mean to be rude, but for the sake of a simple analogy, think of Donald Trump when he was questioned about the need for cyber security: he began talking about how good his ten year old son is with computers.

For a slightly more nuanced perspective: only EU Member states can be members of Europol and benefit from full access to SIENA, which is one of the most sophisticated and well-developed cross-border intelligence networks in the world. When the UK leaves the European Union, our ability for full membership ceases and we must enter into a separate form of agreement for limited participation in information sharing and forgo any kind of strategic or governance over the initiative.

So, yes, we can continue to exchange information. But the ways in which we do that change meaningfully, and to the extent that people I know who work in the security services are dismayed by the thoughtlessness of the discourse.

> highly skilled workers are usually welcome as migrants, aren't they?

Again, this strikes me as simplistic. There seems to be a belief amongst some (not necessarily you) that it's simply one type of form for an EU state importing to the UK, and a different type for a non-EU member.

What we are seeing is the erosion of one of, if not the most open, comprehensive trading blocs ever devised. It is not being replaced by like-for-like systems and benefits for trade and immigration precisely because there is already a system for that: it's called membership of the EU. So take it as read that on a structural level trade and immigration cannot be as simple as they were on reciprocal EU terms. The EU will not allow it.

So it's getting harder to trade with the UK or migrate here. The UK will likely see some short term wins -- small UK offices for organisations, commensurate with our market size -- but our strong position for the establishment of European HQs is significantly damaged.

In a world where skilled migrants can work anywhere, why would they be going to the country which just opted to make it harder to do business? Which has seen its currency collapse since the minutes after the vote in 2016? There are no firm answers in either direction, but you have to do quite a lot of gymnastics to explain why making it harder to trade with us is better in any way.

> As for building "moats" and "walls", I think that is very propagandistic language.

It's very simple. We are making it harder to trade with the European Union. We are making it harder to migrate to and from the European Union. These are not qualitative statements.

It's up to you whether you see this as a necessary moat, or a wall of requirement; or a pointless wall. Same as with Trump and his southern border wall. Some people in the US feel it's urgently needed. Others think those who believe it will have benefits are fantasists. But either way the wall is real.

> Just because you have a moat, doesn't mean people can't come to you. It just means you can decide who is allowed to come and go.

Again, very simplistic. I'll refer you back to the Europol explanation to illustrate how just because something is technically possible, does not mean it is still as likely once it is made artificially difficult.

The United Kingdom, many would argue, is not going to be in position to dictate who is allowed to come and go, in a business sense. We will lose the fight for major investment outside of the financial services sector to European nation states.