Yeah, that looks bad until you look deeper into it.
The Commandant wants the Marines to return to their roots as naval infantry, with special emphasis on island warfare and getting across the beach. Essentially, prepare it for potential war against China on Pacific islands.
To that end, you have ships offshore to provide artillery support - don’t need to bring along anything bigger than a mortar for that.
The US Abrams tank is not capable of swimming to the beach and it is only capable of being transported to the beach by the giant LCAC hovercraft. The problem is that the Abrams is now so heavy that only one Abrams can be transported per LCAC and the needed upgrades to keep it alive in a modern combat environment will soon make it too heavy to even do that.
The Marines are scrapping some amphibious armor but only the oldest. They are buying new, upgrading others and looking to get some completely new systems as well.
Looked at that way it starts to make more sense.
you have ships offshore to provide artillery support -
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Back when ships actually had artillery - now they are mostly missile armed. Therein lies the problem - arty rounds once fired could not be diverted, intercepted, jammed, or fooled. Missiles have all those weaknesses. Worse, those missiles, by in large, depend on GPS guidance at the moment. Giving up HIMARS is a big mistake, not to mention towed arty.
And what if its NOT a beach landing where they are needed? Just because the current nincompoop that runs them has dome romantic idea how to use them, doesn’t mean the enemy will oblige. This leaves the Marines at the mercy of the AF and the Army for support.