Iran launched unsuccessful attack on UK's Diego Garcia

https://www.bbc.com/news/articles/c5yljdgwppzo

Foreign secretary denounces 'reckless Iran threats' after missiles fired at Diego Garcia

Iran reportedly fired two ballistic missiles at Indian Ocean base, but neither reached the target.

The article kind of downplays the most interesting elements. Not an expert, but to my limited understanding:

* I think this is the longest-range use of a ballistic missile in anger, possibly ever?

* This seems to reveal previously-unknown range of Iranian ballistic missiles and, if true, could touch basically all of Europe?

I think the article downplays the element that the attack probably achieved its goal which was not to actually hit something at Diego Garcia, but to show that thing 2500 miles from Iran are potentially targetable by Iran. That starts conversations like the one here and in other fora about whether or not Iran would limit themselves to military targets (Russia doesn't as an example) and if not how could Europe and its East Asian allies protect literally everything with their finite supply of defensive units.

> to show that thing 2500 miles from Iran are potentially targetable

Iran has had IRBMs for some time. Demonstration doesn’t hurt. But demonstrating failure doesn’t particularly help either.

The thing is Iran has long promised their max range was 2k Km and so defensive only. This shows that was a lie.
All countries publicly understate the max range that their missiles can go. This is generally understood in the defense community.
What's the point? Naively one would think it is the opposite.
I heard the same about the number and location of French nuclear war heads, or their exact red lines. If you tell the enemy your limit they're gonna sit exactly on it.