Likely the same as for the Army - the USA has been moving away from heavy armor for some time now - The Stryker sound familiar?
My Uncle Ed (RIP) was a tread head for a short time - then switched to anti-armor unit. Called them (tanks) mulri-ton bullet magnets....
Hard to say when these 70+ ton battle behemoths will ever be used again in any number...
My 60s era tank commander dad called them armored coffins.