I think you are missing something;

The ABM systems we built in the early cold war worked by having nuclear payloads. We could absolutely not hit an incoming ICBM with the tech at the time, so we just slapped a nuke on it and hoped we could get within 1km at detonation.

Importantly, it was a completely dead end. They had no response to MIRVs and could not be built in sufficient numbers to deal with any actual launch. We threw them out because they were in fact useless.

Generally, we have moved away from Nuclear ABM systems because detonating a hundred warheads above a city is very unlikely to work out well.

Intercepting a cold war era ICBM turned out to be feasible with newer technology, and we currently have $2 billion missiles that can feasibly intercept ICBMs (at low quantity).

>No maneuvering boost-glide hypersonic vehicle has ever been fired in combat against a defended target

Nobody has fired one of those against a target because almost nobody has a functioning maneuvering hypersonic vehicle. Basically just China I think.

I would expect "real" hypersonic weapons like that are basically uncounterable. The physics just gets too obnoxious. Interceptors will struggle to get better than a coin flip, and they will be too expensive to use on anything else so they won't be general purpose, so equipping them will be full of tradeoffs.

That's the entire point of hypersonic weapons. $3 billion dollars to make that high value target go away, with extremely high probability. They replace 50 bombers launching still quite expensive anti-ship weapons at scale, which is the strategy it replaces.

This of course has rather negative implications for the concept of force projection in future wars. Which is why China made a hypersonic weapon.